IMPERIAL COLLEGE LONDON
Department of Earth Science and Engineering
Centre for Petroleum Studies
Integration of Residual Hydrocarbon Saturations
From Well Logs Identified Swept Zones Identified in Well Logs with Relative
Permeability
aAnd Core Saturation Data
By
Giri Aridita
A report submitted in partial fulfilment of the requirements for
the MSc and/or the DIC.
September 2010
Style Definition: TOC 2: Left, Nobullets or numbering, Tab stops: 0 cm,Left + Not at 1.75 cm
DECLARATION OF OWN WORK
I declare that this thesis
INTEGRATION OF RESIDUAL HYDROCARBON SATURATIONS FROM WELL LOGS
IDENTIFIED SWEPT ZONES IDENTIFIED IN WELL LOGS WITH RELATIVE
PERMEABILITY AND CORE SATURATION DATA
is entirely my own work and that where any material could be construed as the work of others,
it is fully cited and referenced, and/or with appropriate acknowledgement given.
Signature:
Name of student: Giri Aridita
Name of Imperial College supervisor: Dr. Matthew D. Jackson
Name of company supervisor: Fabrizio Conti (Maersk Oil North Sea UK Limited)
Stephen Milner (Maersk Oil North Sea UK Limited)
Formatted: Line spacing: 1.5 lines
Abstract
The Central North Sea Asset of Maersk Oil UK Ltd. (MOUK) spreads over several oil fields
producing from Paleogene period of clastic reservoirs, where most of the fields are under water injection
or active aquifer support. As the dynamics effect of production and water injection, mMoving oil-water
contacts due to production effects has left behind some residual oil saturation to water (Sorw). The correct
quantification of Sorw is necessary for estimating recoverable reserves, as well as enabling more accurate
reservoir simulation. Sorw value can be acquired from different types of measurement which resultbut
can inconsistent might be obtained due to the uncertainties attributed in each method.
This study aims to compare different methods and reduce the uncertainty in Sorw values in four fields
which are producing from the prolific Balder Massive Sandstones. The fields of interest are located in
different blocks of quad 9 in Central North Sea area, namely Gryphon Maclure, Tullich and Harding
where resemblances in rock and fluid properties are observed.
Several methods based on available open hole log and core analysis dataset were taken to calculate
Sorw. Open hole logs are used to calculate Sorw in the swept zone using Archie equation, in which the
electrical properties are derived from Special Core Analysis (SCAL) data. Uncertainties in Archie
parameters are also captured to generate a range of values of Sorw from log analysis, and core saturation
data from Dean Stark analysis is used to verify log-derived saturation.
Oil-water relative permeability data from unsteady-state test are used to find Sorw values whenat zero
oil relative permeability have been achieved. Validity of the results from each core sample is investigated
to exclude samples that are affected by capillary effect and end effect that overestimate the Sorw value.
Coreflood test result was also analyzed to find Sorw after laboratory waterflooding test, and it shows the
relation of oil saturation to the amount of pore volume (PV) water injected. To see the extent of PV water
injected to Sorw in reservoir condition, an attempt to replicate Buckley Leverett-derived plot
displacement to from the log data was made. The result then compared to core derived Buckley Leverett
analysis for verification. An observation to the existing simulation model result also indicates that the
relation exists in the case of advancing oil-water contact.
Archie equation is found to be reliable in clean Balder Massive Sandstone shown by previous in-house
study,. and the lLog derived Sorw give a most likely range of 10-20% with a variation of range observed
in different well samples. Oil-water relative permeability analysis comes up with the range of 16-30%
with the mode of 20%. Core flood data shows that Sorw in the range of 10-30% and is inversely
proportional to the amount of water injected. It also indicates that true residual oil saturation in Balder
Formation might not be achieved until the injection of many PV of water. This could be interpreted that
observed Sorw will be reduced as the oil-water contact is advancing.
After data reconciliation, the selected values of Sorw are 10%, 20%, and 30% for the P10, P50, and
P90 respectively. Each value then is used to re-scale existing relative permeability data set to see how
different Sorw will impact the ultimate oil recovery. The simulation model then run to make prediction
until the end of oil production in 2018 and it change the ultimate recovery of ±6 % or -5.5 to +8 MMSTB
in the remaining reserves.
Formatted: English (U.K.)
Formatted: para
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
I List of Figures
Formatted: No underline
Formatted: Border: Top: (Single solidline, Auto, 0.5 pt Line width)
Formatted: No underline
LIST OF FIGURES
Figure 1 Gryphon Simulation Model ..................................................................................... Error! Bookmark not defined.3
Figure 2 Cross Section of Gryphon Simulation Model Showing Movement in OWC .... Error! Bookmark not defined.3
Figure 4 Comparison of Log and Core Porosity.................................................................. Error! Bookmark not defined.9
Figure 9 Kv Distributions in Sector Model .......................................................................... Error! Bookmark not defined.12
Figure 12 Sor Reconciliation ................................................................................................ Error! Bookmark not defined.12
Figure 11 Relative Permeability Data and Curve-fitted Corey Model ............................ Error! Bookmark not defined.12
Figure 13 Relative Permeability Model for Flow Simulation ............................................ Error! Bookmark not defined.12
Figure 14 Impact of Different Sor to Ultimate Oil Recovery ............................................ Error! Bookmark not defined.13
Figure 15 Sensitivity Analysis of Archie Equation ............................................................ Error! Bookmark not defined.13
Figure 16 Effect of Petrophysical Properties to Sor and Corey Exponents .................. Error! Bookmark not defined.14
Figure 1 Gryphon Simulation Model ......................................................................................................................................... 3
Figure 2 Cross Section of Gryphon Simulation Model Showing Movement in OWC ........................................................ 3
Figure 3 Relative Permeability Curve Refinement Work Flow .............................................................................................. 7
Figure 4 Comparison of Log and Core Porosity...................................................................................................................... 9
Figure 5 Residual Oil Saturation in Open Hole Log ............................................................................................................. 10
Figure 7 Sorw Histogram from Relative Permeability Analysis .......................................................................................... 10
Figure 8 Laboratory Core Water Flood Test Result ............................................................................................................. 11
Figure 9 Buckley Leverett Analysis on Refined Water-Oil Relative Permeability Data ................................................... 11
Figure 10 Sector Model Showing Decreasing Oil Saturation in Rising Oil Water Contact ............................................. 11
Figure 11 Kv Distribution in Sector Model ............................................................................................................................. 11
Figure 12 Relative Permeability Data and Curve-fitted Corey Model ................................................................................ 12
Figure 13 Sor Reconciliation .................................................................................................................................................... 12
Figure 14 Relative Permeability Model for Flow Simulation ................................................................................................ 12
Figure 15 Impact of Different Sor to Ultimate Oil Recovery ................................................................................................ 12
Figure 16 Partial Error Contribution from Archie Constant .................................................................................................. 13
Figure 17 Effect of Petrophysical Properties to Sor and Corey Exponents ...................................................................... 13
Fig. 1 Field location map (right) and schematics of fields boundaries (left) ........................................................................ 3
Fig. 2 Cross section of gryphon simulation model showing movement in OWC in the forms of water cusping around
horizontal production wells and moving free water level at a larger scale. ......................................................................... 4
Fig. 3 Reservoir wettability data measured from various type of core plugs. Fresh state plugs show a variety of
wettability state from strongly oil wet to weakly water wet .................................................................................................... 4
Fig. 4 Relative permeability curve refinement work flow as suggested by Stiles [2004] from raw data ......................... 8
Fig. 5 Comparison of log and core porosity ........................................................................................................................... 10
Fig. 6 Sorw Histogram from Relative Permeability Analysis ............................................................................................... 10
Fig. 7 Residual oil saturation in open hole log ...................................................................................................................... 11
Fig. 9 Buckley Leverett analysis on refined water-oil relative permeability data from (a) all available data and (b)
validated data from screening criteria superimposed with replicated log-derived curve ................................................ 12
Fig. 10 Kv distributions in sector model ................................................................................................................................. 12
Formatted: Font: (Default) Arial
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
II Table of Contents - AppendicesList of Tables
Formatted: Border: Top: (Single solidline, Auto, 0.5 pt Line width), Bottom:(No border), Tab stops: 16.2 cm,Centered + 18 cm, Right
Fig. 11Sector model from Gryphon full field model showing decreasing oil saturation in the swept zones as oil water
contact is increasing .................................................................................................................................................................. 12
Fig. 12 Sor reconciliation from different measurements ...................................................................................................... 13
Fig. 13 Relative Permeability Data and Curve-fitted Corey Model ..................................................................................... 13
Fig. 14 Relative Permeability Model for Flow Simulation .................................................................................................... 13
Fig. 15 Impact of different sor to ultimate oil recovery ......................................................................................................... 14
Fig. 16 Sensitivity analysis of archie equation ...................................................................................................................... 15
Fig. 1 Effect of petrophysical properties to Sor and Corey exponents…………………………………………………15
Field Code Changed
Formatted: Font: (Default) Times NewRoman
Formatted: Font: (Default) Arial
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
III List of Figures
Formatted: No underline
Formatted: Border: Top: (Single solidline, Auto, 0.5 pt Line width)
Formatted: No underline
LIST OF TABLES
Table 1 Residual Oil Saturation in Different Fields ................................................................................................................. 2
Table 2 Summary of Fluid Contacts ......................................................................................................................................... 3
Table 3 Summary of Rock and Fluid Properties ..................................................................................................................... 3
Table 4 Number of Samples Available from Various SCAL Analyses ............................................................................... 54
Table 5 Values of Corey Exponent for Different Type of Wettability .................................................................................. 65
Table 6 Range of Values for Screening Criteria ................................................................................................................... 87
Table 7 Archie Equation Parameters .................................................................................................................................... 109
Table 8 Uncertainties in Archie Parameters ........................................................................................................................ 109
Table 9 Residual Saturation from Open Hole Log .............................................................................................................. 109
Table 10 Relative Permeability End Points for Sensitivity Analysis ............................................................................... 1412
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
IV Table of Contents - AppendicesList of Tables
Formatted: Border: Top: (Single solidline, Auto, 0.5 pt Line width), Bottom:(No border), Tab stops: 16.2 cm,Centered + 18 cm, Right
TABLE OF CONTENTS - APPENDICES
APPENDIX 1: Critical Literature Review 11
A1.1 SPE 3791 - Determination of Residual Oil Saturation After Water flooding
44
A1.2 SPE 14887 - Evaluation and Comparison of Residual Oil Saturation Determination Techniques
55
A1.3 SPE 30763 - Dependence of Waterflood Remaining Oil Saturation on Relative Permeability, Capillary Pressure, and
Reserrvoir Parameters in Mixed Wet Turbidite Sands 66
A1.4 SPE 19851 - Field Wide Variations in Residual Oil Saturation in a Sea Sandstone Reservoir
77
A1.5 SPE 88628 Residual Oil Saturation Analysis of The Burgan Fromation in the Greater Burgan Field, Kuwait.
88
A1.6 SPE 16471 Wettability Literature Survey-Part 6: The Effects of Wettability on Waterflooding
99
A1.7 SPWLA 1986-vXXVIIn5a3 Sensitivity Analysis of The Parameters In Archie''s Water Saturation Equation
1010
A1.8 SPWLA 2004-UUU EVALUATION OF RESIDUAL OIL SATURATION IN THE BALMORAL FIELD (UKCS)
1111
A1.9 SPE 39038 Optimal Design and Planning for Laboratory Corefloods
1212
A1.1010 SPE 17686 Residual Oil Saturations Determined by Core Analysis
1313
A1.11 SPE 3785 Reservoir Waterflood Residual Oil Saturation from Laboratory Tests
1414
A1.12 SPE 3786 Core and Log Determination of Residual Oil After Waterflooding - Two Case Histories.
1515
A1.13 SPE 3795 Determination of Residual Oil Saturation From Time-Lapse Pulsed Neutron Capture Logs in a Large
Sandstone Reservoir. 1616
A1.14 SPE 77545 A Unified Theory on Residual Oil Saturation and Irreducible Water Saturation.
1717
A1.15 SPE 22903-MS Determining Effective Residual Oil Saturation for Mixed Wettability Reservoirs: Endicott Field, Alaska.
1818
APPENDIX 2: Field Description Figures
1919
APPENDIX 3: Log Analysis
2727
Formatted: Font: Times New Roman,16 pt, Not Bold, Font color: Auto
Formatted: Centered, Space Before: 0 pt, Line spacing: single
Formatted: Font: 10 pt
Formatted: No bullets or numbering
Formatted: No bullets or numbering
Formatted: Heading 1, Outlinenumbered + Level: 1 + NumberingStyle: 1, 2, 3, … + Start at: 1 +Alignment: Left + Aligned at: 0 cm +Tab after: 0 cm + Indent at: 0 cm
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
V Table of Contents - Appendices
Formatted: No underline
Formatted: Border: Top: (Single solidline, Auto, 0.5 pt Line width)
Formatted: No underline
APPENDIX 4: Core Analysis
2929
APPENDIX 5: Relative Permeability Data Refinement
3232
APPENDIX 6: Buckley Leverett Calculations
3838
APPENDIX 7: Impact of SORW to Recovery Prediction and History Match
3939
APPENDIX 1: Critical Literature Review 1
A1.1 SPE 3791 - Determination of Residual Oil Saturation After Water flooding
4
A1.2 SPE 14887 - Evaluation and Comparison of Residual Oil Saturation Determination Techniques
5
A1.3 SPE 30763 - Dependence of Waterflood Remaining Oil Saturation on Relative Permeability, Capillary Pressure, and
Reservoir Parameters in Mixed Wet Turbidite Sands 6
A1.4 SPE 19851 - Field Wide Variations in Residual Oil Saturation in a Sea Sandstone Reservoir
7
A1.5 SPE 88628 Residual Oil Saturation Analysis of The Burgan Fromation in the Greater Burgan Field, Kuwait.
8
A1.6 SPE 16471 Wettability Literature Survey-Part 6: The Effects of Wettability on Waterflooding
9
A1.7 SPWLA 1986-vXXVIIn5a3 Sensitivity Analysis of The Parameters In Archie''s Water Saturation Equation
10
A1.8 SPWLA 2004-UUU EVALUATION OF RESIDUAL OIL SATURATION IN THE BALMORAL FIELD (UKCS)
11
A1.9 SPE 39038 Optimal Design and Planning for Laboratory Corefloods
12
A1.10 SPE 17686 Residual Oil Saturations Determined by Core Analysis
13
A1.11 SPE 3785 Reservoir Waterflood Residual Oil Saturation from Laboratory Tests
14
A1.12 SPE 3786 Core and Log Determination of Residual Oil After Waterflooding - Two Case Histories.
15
A1.13 SPE 3795 Determination of Residual Oil Saturation From Time-Lapse Pulsed Neutron Capture Logs in a Large
Sandstone Reservoir. 16
A1.14 SPE 77545 A Unified Theory on Residual Oil Saturation and Irreducible Water Saturation.
17
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
VI Table of Contents - AppendicesList of Tables
Formatted: Border: Top: (Single solidline, Auto, 0.5 pt Line width), Bottom:(No border), Tab stops: 16.2 cm,Centered + 18 cm, Right
A1.15 SPE 22903-MS Determining Effective Residual Oil Saturation for Mixed Wettability Reservoirs: Endicott Field, Alaska.
18
APPENDIX 2: Field Descriptions 19
Archie Constants Calculation 25
Log Analysis 27
27
Core Analysis 29
Relative Permeability Data Refinement 32
Buckley Leverett Calculations 38
Impact of SORW to Recovery Prediction and History Match 39
APPENDIX 1: APPENDIX 1: Critical Literature Review 1
A.1 1 SPE 3791 Determination of Residual Oil Saturation After Water flooding 4
TABLE OF CONTENTS - APPENDICES
APPENDIX - 1 Critical Literature Review 1
APPENDIX - 2 Field Descriptions 2
APPENDIX - 3 Archie Constants Calculation 3
APPENDIX - 4 Relative Permeability Data Refinement 4
APPENDIX - 5 Core Analysis Procedures 5
APPENDIX - 6 Buckley Leverett Calculations 6
APPENDIX - 7 Impact of SORW to Recovery Prediction and History Match 7
Formatted: Space Before: Auto,After: Auto, Line spacing: single
Formatted: Space Before: Auto,After: Auto
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
VII List of FiguresTable - Appendicesx
Formatted: No underline
Formatted: Border: Top: (Single solidline, Auto, 0.5 pt Line width)
Formatted: No underline
LIST OF FIGURES - APPENDICES
Figure A 1 Net Sand Map of Gryphon Area with the Locations of Cored Wells ......................................................................... 19
Figure A 2 Core photograph of Well 9/18b-7 Showing Oil Bearing Sandstone .......................................................................... 19
Figure A 3 Type Log of Gryphon Area Showing Balder Massive Sandstone .............................................................................. 20
Figure A 4 Composite RFT Data from Gyphon ........................................................................................................................... 21
Figure A 5 Porosity Permeability Cross Plot of Balder Massive Sandstone ................................................................................ 21
Figure A 6 Kv/Kh Cross Plot of Balder Massive Sandstone ........................................................................................................ 21
Figure A 7 North South Schematic Cross Section of Gryphon Field ........................................................................................... 22
Figure A 8 West East Seismic Cross Section of Gryphon Field .................................................................................................. 22
Figure A 9 North South Schematic Cross Section of Harding and Tullich Field ......................................................................... 23
Figure A 10 North South Schematic Cross Section of Maclure Field .......................................................................................... 23
Figure A 11 Histogram of Core Derived Cementation Factor ..................................................................................................... 25
Figure A 12 Histogram of Core Derived Saturation Exponent .................................................................................................... 25
Figure A 13 Histogram of Log Derived Apparent Water Resistivity (Rwa) ................................................................................ 26
Figure A 14 Harding Well 9/23b-A29 Open Hole Log ................................................................................................................ 27
Figure A 15 Gryphon Well 9/18b-30A Open Hole Log ............................................................................................................... 28
Figure A 18 Pie Chart of the Number of Plugs for Different SCAL Analysis in Harding Field .................................................. 29
Figure A 17 Pie Chart of the Number of Plugs for Different SCAL Analysis in Gryphon Field ................................................. 29
Figure A 16 Pie Chart of the Number of SCAL Wells ................................................................................................................. 29
Figure A 19 Pie Chart of the Number of Plugs for Different SCAL Analysis in Maclure Field .................................................. 30
Figure A 20 Pie Chart of the Number of Plugs for Different SCAL Analysis in Tullich Field ................................................... 30
Figure A 21 Histogram of Oil Saturation From Dean Stark Analysis .......................................................................................... 31
Figure A 21 Workflow of Buckley Leverett Analysis to Calculate Oil Saturation as A Function of PV Water Sweep .............. 38
Figure A 23 Comparison of Field Water Production Rate from Different Sor Cases with Actual Production Rate .................... 39
Figure A 22 Comparison of Field Oil Production Rate from Different Sor Cases with Actual Production Rate ......................... 39
Figure A 25 Comparison of Field Gas Production Rate from Different Sor Cases with Actual Production Rate ....................... 40
Figure A 24 Comparison of Field Water Cut Production Rate from Different Sor Cases with Actual Production Rate ............. 40
Figure A 1 Net Sand Map of Gryphon Area with the Locations of Cored Wells ......................................................................... 19
Figure A 2 Core photograph of Well 9/18b-7 Showing Oil Bearing Sandstone .......................................................................... 19
Figure A 3 Type Log of Gryphon Area Showing Balder Massive Sandstone .............................................................................. 20
Figure A 4 Composite RFT Data from Gyphon ........................................................................................................................... 21
Figure A 5 Porosity Permeability Cross Plot of Balder Massive Sandstone ................................................................................ 21
Figure A 6 Kv/Kh Cross Plot of Balder Massive Sandstone ........................................................................................................ 21
Figure A 7 North South Schematic Cross Section of Gryphon Field ........................................................................................... 22
Figure A 8 West East Seismic Cross Section of Gryphon Field .................................................................................................. 22
Figure A 9 North South Schematic Cross Section of Harding and Tullich Field ......................................................................... 23
Figure A 10 North South Schematic Cross Section of Maclure Field .......................................................................................... 23
Figure A 11 Histogram of Core Derived Cementation Factor ..................................................................................................... 25
Figure A 12 Histogram of Core Derived Saturation Exponent .................................................................................................... 25
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
VIII List of Figures - Appendices
Figure A 13 Histogram of Log Derived Apparent Water Resistivity (Rwa) ................................................................................ 26
Figure A 14 Harding Well 9/23b-A29 Open Hole Log ................................................................................................................ 27
Figure A 17 Pie Chart of the Number of Plugs for Different SCAL Analysis in Harding Field .................................................. 29
Figure A 16 Pie Chart of the Number of Plugs for Different SCAL Analysis in Gryphon Field ................................................. 29
Figure A 18 Pie Chart of the Number of SCAL Wells ................................................................................................................. 29
Figure A 18 Pie Chart of the Number of Plugs for Different SCAL Analysis in Maclure Field .................................................. 30
Figure A 19 Pie Chart of the Number of Plugs for Different SCAL Analysis in Tullich Field ................................................... 30
Figure A 20 Histogram of Oil Saturation From Dean Stark Analysis .......................................................................................... 31
Figure A 21 Workflow of Buckley Leverett Analysis to Calculate Oil Saturation as A Function of PV Water Sweep .............. 38
Figure A 23 Comparison of Field Water Production Rate from Different Sor Cases with Actual Production Rate .................... 39
Figure A 22 Comparison of Field Oil Production Rate from Different Sor Cases with Actual Production Rate ......................... 39
Figure A 25 Comparison of Field Gas Production Rate from Different Sor Cases with Actual Production Rate ....................... 40
Figure A 24 Comparison of Field Water Cut Production Rate from Different Sor Cases with Actual Production Rate ............. 40
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
IX List of Table - Appendices
LIST OF TABLES - APPENDICES
Table A 1 Reservoir Oil Properties..............................................................................................24
Table A 2 Formation Water Properties……………………………………………………………….24
Formatted: Font: (Default) Arial, 12 pt
Formatted: Left
Formatted: Font: Not Bold
Formatted: Font: Not Bold
Formatted: Font: Not Bold
Formatted: Font: Not Bold
Formatted: Left
Abstract
The Central North Sea Asset of Maersk Oil UK Ltd. (MOUK) spreads over several oil fields producing from Paleogene
period of clastic reservoirs, where most of the fields are under water injection or active aquifer support. As the dynamics effect
of production and water injection, moving oil-water contacts has left behind some residual oil saturation to water (Sorw). The
correct quantification of Sorw is necessary for estimating recoverable reserves, as well as enabling more accurate reservoir
simulation. Sorw value can be acquired from different types of measurement which result can inconsistent due to the
uncertainties attributed in each method.
This study aims to compare different methods and reduce the uncertainty in Sorw values in four fields which are producing
from the prolific Balder Massive Sandstones. The fields of interest are located in different blocks of quad 9 in Central Sea
area, namely Gryphon Maclure, Tullich and Harding where resemblances in rock and fluid properties are observed.
Several methods based on available open hole log and core analysis dataset were taken to calculate Sorw. Open hole logs
are used to calculate Sorw in the swept zone using Archie formequation, in which the electrical properties are derived from
Special Core Analysis (SCAL) data. Uncertainties in Archie parameters are also captured to generate a range of values of Sorw
from log analysis, and core saturation data from Dean Stark analysis is used to verify log-derived saturation.
Oil-water relative permeability data from unsteady-state test are used to find Sorw values at zero oil relative permeability.
Validity of result from each core sample is investigated to exclude samples that affected by capillary effect and end effect that
overestimate the Sorw value. Coreflood test result was also analyzed to find Sorw after laboratory waterflooding test, and it
shows the relation of oil saturation to the amount of pore volume (PV) water injected. To see the extent of PV water injected to
Sorw in reservoir condition, an attempt to replicate Buckley Leverett displacement to log data was made. The result then
compared to core derived Buckley Leverett analysis for verification. An observation to the existing simulation model result
also indicates that the relation exists in the case of advancing oil-water contact.
Archie formequation is found to be reliable in clean Balder Massive Sandstone, and the log derived Sorw give a most likely
range of 10-20% with a variation of range observed in different well samples. Oil-water relative permeability analysis comes
up with the range of 16-30% with the mode of 20%. Core flood data shows that Sorw in the range of 10-30% and is inversely
proportional to the amount of water injected. It also indicates that true residual oil saturation in Balder FormFormation might
not be achieved until the injection of many PV of water. This could be interpreted that observed Sorw will be reduced as the
oil-water contact is advancing.
After data reconciliation, the selected values of Sorw are 10%, 20%, and 30% for the P10, P50, and P90 respectively. Each
value then is used to re-scale existing relative permeability data set to see how different Sorw will impact the ultimate oil
recovery. The simulation model then run to make prediction until the end of oil production in 2018 and it change the ultimate
recovery of ±6 XX-XX% andor -XX-XX5.5 to +8 MMSTB in the remaining reserves.
Introduction
Residual oil saturation (Sor) is an important parameter for reserves evaluation and reservoir simulation. It is also an
indicator the potential of a tertiary recovery being applied in the respective field. Review on Sor is normally carried out in a
field under secondary recovery of waterflooding, where some amount of oil is left behind the flood front. The same
phenomenon of residual oil saturation to water (Sorw) is also observed in the swept zone of advancing oil -water contact. An
accurate determination of Sor could provide the basis of refining the recovery factor prediction and possibility to increase
field’s reserve estimation.
The term of residual oil saturation has a loose definition as pointed out by several author such as [Al-Sabea [, 2004],
[Chang, [1988], [Hirasaki, [1996], [Strange, [1972] and [Valenti, [2002]. It is defined as (a) the fraction of the pore volume
that contains oil which cannot be displaced by immiscible fluid [Strange, [1972]15
. (b) The lowest oil saturation that a reservoir
INTEGRATION OF RESIDUAL HYDROCARBON SATURATIONS FROM WELL LOGS IDENTIFIED SWEPT ZONES IDENTIFIED IN WELL LOGS WITH RELATIVE PERMEABILITY AND CORE SATURATION DATA
Student name: Giri Aridita
Imperial College supervisor: Dr. Matthew D. Jackson
Company supervisor(s): Fabrizio Conti (Maersk Oil North Sea UK Ltd.)
Stephen Milner (Maersk Oil North Sea UK Ltd.)
Imperial College
London
Formatted: Font: (Default) Arial, NotBold
Formatted: Font: 12 pt, Not Bold
Formatted: Font: (Default) Arial, NotBold
Formatted: Font: (Default) Arial, 12 pt
Formatted: Font: (Default) Arial, NotBold
Formatted: None, Don't lock anchor,Position: Horizontal: Left, Relative to:Column, Vertical: In line, Relative to:Margin, Horizontal: 0 cm, Width: Auto,Height: Auto, Wrap Around
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
XII List of Tables - Appendicesx
Formatted: Border: Top: (Single solidline, Auto, 0.5 pt Line width), Bottom:(No border)
Field Code Changed
can technically achieved in a given recovery mechanism1
[Al-Sabea, [2004]. (c) It might also be defined according to the
physical
2
condition that resulted in such as saturation at which the oil relative permeability reaches zero [Hirasaki [, 1996]. (d) In
laboratory core measurement it is defined as final saturation value at the end of displacement, (e) whereas on the field level it
is defined as the saturation in the swept zone, which relates the Sorw to the amount of water sweeping the reservoir16
.Another
perspective is that (f) the displacement.
(e) On the field level it is defined as the saturation in the swept zone, which relates the Sorw to the amount of water
sweeping the reservoir [Chang, [1988]. Another perspective is that (f) the remaining oil saturation is a measure of how far the
process has travelled along the Kro curve at the time it is terminated. In this study, the term of residual oil saturation refers to
the saturation at the end of displacement process both in the reservoir and the laboratory.
Previous author16
which utilized Pulsed Neutron Capture (PNC) log to monitor saturation behind casing in a naturally
water swept zonesfield under water flood. The result shows that after the water swept an interval, the oil saturation would
continue to decrease over time as the water is sweeping over an interval [Syed, [1991]. Another study shows that residual oil
saturation in mixed wettability reservoirs is a strong function of pore volume (PV) water injected [Wood, [1991]. This is
because oil is only trapped in the large oil-wet pores and creates connected paths along the pore walls. Thus oil permeability
will always exist even in the very low oil saturation, allowing oil to be displaced as more PV of water is injected.
One way to calculate Sorw is by calculating oil saturation from open hole log data in the swept zone, which is considered
as in-situ single well measurement [Chang, [1988]. However the true residual oil saturation is frequently not met until a
reservoir has been swept for many years. The accuracy of this method is largely affected by the value of the electrical
constants in water saturation equation, porosity, and type of resistivity tool being used [Al-Sabea [, 2004].
Special Core Analysis (SCAL) provides different type Sorw measurements which normally include core flood analysis,
relative permeability measurement, and centrifuge capillary pressure measurement. Routine Core Analysis (RCAL) study also
provides saturation measurement by means of Dean Stark analysis. Frequently different methods of measurement do not yield
consistent answers; therefore comparison of results is an alternative for Sorw evaluation.
Laboratory displacement tests provides an estimate of residual oil saturation after water flooding, but the results may vary
depends on test condition, sample condition, and procedure which is taken. These issues increase the uncertainty of results,
and validity of the test become an important concern before taking the value of Sorw as a reference. In an oil-water
displacement test it is necessary to mimics actual reservoir condition by carry out the test in reservoir temperature and using
reservoir fluids [Kennaird, [1988]. Limitation in core plug size and available tool sometimes made the test could only be
conducted for a narrow range of measurement which makes the result become inaccurate.
There is a number of publications which attempted to integrate Sorw from core and log analysis data. Al Sabea ([2004])
investigated Sorw in a waterflooded Burqan Field in Kuwait by comparing open hole log data, cased hole log data, and core
flood data. He also investigated different Sorw values for different rock type and related the change in Sorw with time using
pulse neutron log data. Chang [(1988]) compared several methods of Sorw measurement both by single well and multi well
techniques. Cordiner [(1972]) supplemented core and log analysis with material balance method. Strange [(1972]) investigated
the effect of different coring methods to Sorw and compare it with open hole log results. All authors found a good agreement
between core and log data, however the accuracy of results may varies depend on the number of rock types and reservoir
heterogeneity.
Currently, various studies in Maersk Oil UK Ltd. (MOUK) only rely on core derived Sorw, and none of the effort ever
consider an integration and reconciliation of various data sources and relate the remaining oil saturation with the amount of
water sweep. Table 1 summarises the Sorw values from water-oil relative permeability end points in the fields of interest.
This study aims to compare Sorw values obtained from different methods after reducing uncertainties attributed in each
method. The Sorw comes from open hole logs, unsteady state oil-water relative permeability test, and waterflood test, and
Dean Stark analysis. Emphasized on the limitation for each method is presented and relation of Sorw to pore volume (PV) of
water injected is investigated. The deliverable result is a new range of Sorw values which will be implemented to the existing
reservoir simulation model to re-forecast recoverable reserves before gas cap blowdown in 2018..
Field description and geology
Gryphon area consists of the main Gryphon field with the surrounding smaller fields which are Maclure, Tullich and
Harding. All the fields produce from Palaeocene age Balder FormFormation which comprises of clean, well-sorted, fine to
medium grain, and poorly cemented sandstone as described by [Newman, [1993] with joined estimated P50 STOIIP of 600
MMstb. It is located in the South Viking Graben Area of the Central North Sea Block 9/18b, 9/18a, 9/23a, and 9/23b
Table 1 Residual Oil Saturation in Different Fields
Field Sorw Range Normalized Sorw Source
Tullich 0.22 - 0.38 0.25 Core
Gryphon 0.09 - 0.44 0.24 Core
Harding 0.24 - 0.26 0.26 Core
Maclure 0.18 - 0.35 0.27 Core
Field Sorw Range Normalized Sorw Source
Tullich 0.22 - 0.38 0.25 Core
Gryphon 0.09 - 0.44 0.24 Core
Harding 0.24 - 0.26 0.26 Core
Maclure 0.18 - 0.35 0.27 Core
Formatted Table
Formatted: Indent: First line: 0 cm
Formatted: Indent: First line: 0 cm
3
Gryphon
Harding
Tullich
MaclureGryphon
Harding
Tullich
Maclure
respectively, 320 km east of Aberdeen. The first hydrocarbon accumulation was discovered by exploration well 9/18b-7 in
Gryphon prospect in 1987 that encountered 405ft of gross reservoir with 325ft net hydrocarbon pay-zone. Further exploration
subsequently discovered smaller oil accumulation in Maclure and Tullich, and Harding in 1991.
All the fields are deposited in turbidite environments with a combination of stratigraphic and dip closure trap overlain by
gas cap and underlain by large aquifer. Fluid contacts are observed from large numbers of well logs and confirmed by RFT
data prior to production as shown in Appendix II.
Previous study shows that Gryphon, Tullich and Harding are underlain by the same aquifer which is shown by water
compositional analysis and pressure gradient. Meanwhile Maclure is underlain by different and weaker aquifer which is not
connected to Gryphon’s. Despite having separate contacts all field are hydrostatistically balanced and it was observed that
there is direct pressure communication through the gas cap. Table 2 summarise original fluid contacts in all fields.
Table 2 Summary of Fluid Contacts
Table 2 Summary of Fluid Contacts
The majority of reserves in the Gryphon area are contained in high quality Balder Massive Sandstone, with some contained
in the injection wings, a geological feature where the original sand body are remobilised. The unconsolidated sandstone
resulted high porosity and high permeability reservoir with average net to gross ratio up to 98% and Kv/Kh ratio close to unity
as shown in Appendix II. Cross-plot of core porosity and permeability which shown in Appendix II shows the trend of single
rock type exist in the reservoir. Balder Sandstone contains saturated heavy oil with high viscosity which range from 20-26
API with viscosity from the lowest 3.2 cP in Tullich to the highest 7.5 cP in Gryphon. Typical reservoir and fluid properties
for Balder FormFormation are summarized in table 3.
Table 3 Summary of Rock and Fluid Properties
Field Por (%) k (D) N/G (%)
Gross Thickness (ft) API
Viscosity (cp)
GOR (scf/bbl)
Bubble Point (deg F)
Tullich 30 1 98 30-59 26 3.2 316 2450
Gryphon 33 6 98 400-650 21.5 7.5 270 2510
Harding 35 8-10 99 250 22 5 238 2480
Maclure 33 4.5 98 150 26.5 2.6 330 2503
Fig. 2 Field location map (right) and schematics of fields boundaries (left)
Field Initial GOC (ft-ss) Initial OWCWOC (ft-ss) Initial Pressure at GOC (psi)
Tullich 5525 (North) & 5475 (South) 5735 2450
Gryphon 5541 5731 2510
Harding 5541 5804 2480
Maclure 5497 ( North Lobe) & 5541 (South Lobe) 5806 (South Lobe) 2503
Aberdeen
Formatted: Centered
Formatted: Font: (Default) Arial, 8 pt
Formatted: Don't keep with next,Position: Vertical: Top, Relative to:Paragraph, Height: Exactly 0.45 cm
Field Code Changed
Formatted: Caption, Centered, Indent:First line: 0 cm, Keep with next
Formatted: Font: (Default) Arial,English (U.S.)
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Indent: First line: 0 cm
Formatted: Caption, Centered, Indent:First line: 0 cm
Formatted: Font: (Default) Arial, NotBold, English (U.S.)
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Justified
Formatted: Centered
4
Table 3 Summary of Rock and Fluid Properties
Oil recovery mechanism in the Gryphon area is dominated by strong aquifer drive and augmented by water injection in the
water leg. Fluid withdrawal from the oil column together with active aquifer influx and water injection has made the oil-water
contact risen both in formform of local water coning and increase of the water tablefree water level. Unfavourable mobility
ratio in the fields also makes the reservoir very prone to water coning. Well logs from recently drilled wells in Gryphon and
Harding exhibit an evidence of moving oil water contact which leaves some residual oil saturation behind. These findings
might be taken as the lowest actual saturation that could be achieved in the given reservoir condition. However some questions
arise whether the saturation will keep decreasing as the advancing oil-water contact moves further up-structure, as the water
might have not completely displaced the mobile oil fraction. The history matched simulation model from Gryphon shows that
water cusping occurred in horizontal producers and created local swept zones as shown on figure 2.
Literature Review
Review on Available Core Data
Coring operation were conducted using 8.5 in core bit mostly using oil-based / bland mud as drilling fluid with fiberglass
core sleeve. Since the reservoir section is highly unconsolidated, great care was taken to recover core with the minimum of
damage, and the core was frozen at the wellsite. A total number of 4000ft core sample was recovered from Gryphon, and the
other fields, followed by routine and special core analysis. The detailed procedures for routine and special core analysis
measurements are explained in Appendix 5..
Oil-water relative permeability analysis was conducted using unsteady state methods using both fresh state and cleaned
state plugs. The test was conducted in low rates in the range of 3 – 10 cc/min using refined mineral oil which viscosity is
modified to match the viscosity ratio in reservoir condition of 11:1. The experiments were done at ambient temperature and
elevated overburden pressure of 1500 and 2200 psi. Water flood susceptibility analysis (WFS) was conducted using both
cleaned state and fresh state plugs at reservoir condition using the same refined mineral oil used in the relative permeability
measeurement.
Wettability data was measured using AAmottMOTT and USBM method on fresh, cleaned, and restored plugs. The
observed wettability data shows that Balder Massive Sandstone comprises of mixed, intermediate, and neutral wet rock as
described in [Gryphon FDP [, 1992] and is shown on figure 3..
Fig. gure 1 Gryphon sSimulation mModel
Fig.ure 2 Fig. 3 Cross sSection of gGryphon sSimulation mModel sShowing mMovement in OWC in the forms of water cusping
around horizontal production wells and moving free water level at a larger scale.
Moving free water level
Water cusping
Formatted: Indent: First line: 0 cm
Formatted: Position: Horizontal: 2.17cm, Relative to: Page, Vertical: 0.65cm, Relative to: Paragraph, Width:Exactly 17.17 cm, Height: Exactly 0.8cm
Field Code Changed
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Highlight
Formatted: Indent: First line: 0.5 cm
Formatted: Font: Times New Roman,Not Bold
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Centered
5
Wettability Effect To Sor
0
10
20
30
40
50
60
0 0.2 0.4 0.6 0.8 1
Wettability Index to Water
So
r (%
)
Clean State
Fresh State
Restored State
Poly. (Fresh State)
eElectrical properties measurements including formation resistivity factor and formation resistivity index are conducted
under ambient temperature condition and overburden pressure up to reservoir pressure using cleaned state and fresh state
plugs.. Table 4 summarise the type of SCAL analysis with the corresponding number of samples.
Core water flood test results are available from 39 fresh and cleaned states samples from Gryphon and Maclure with
sample dimension of 1.5 inch diameter and 2-3 inch length
There are 280 conventional core plug samples that went through oil saturation analysis using Dean Stark extraction
method. The plugs are taken from the clean sandstones zones in the oil and water legs. The method uses extraction of oil under
reflux of alternating toluene and methanol as solvents. Dean Stark saturation data is used as a quality check of log-derived
saturation for both oil and water.
Table 4 Number of Samples Available from Various SCAL Analyses Core water flood test results are available from 39 fresh and cleaned states samples from Gryphon and Maclure with sample
dimension of 1.5 inch diameter and 2-3 inch length. The available data then compared to see the effect of the amount of pore
volume (PV) of water sweep to Sorw. Buckley Leverett analysis was conducted to all refined oil-water relative permeability
curves to present theoretical relation of Sorw to the amount of PV water injected which was not achieved during the water
flood test. The calculation details of Buckley Leverett method is presented in Appendix III
AnAnalysis No of Samples
Tullich Gryphon Harding Maclure
Unsteady State Kro-Krw 8 55 13 13
Water flood 0 33 6 0
Wettability 0 71 0 6
Electrical Properties 8 87 43 13
Table 4 Number of Samples Available from Various SCAL Analyses
Open-Hole Log Data Review
Open-hole log data sets from all fields are available from both original borehole and sidetracks. From which majority
(>80%) were drilled using oil-based mud and the remaining using water based mud. Discovery and appraisal wells were
logged by wireline and most of development wells by Logging While Drilling (LWD) tool. Early appraisal wells were logged
using wireline log with Sstandard set of triple combo which consists of gamma-ray; calliper, sonic, density, neutron, and
resistivity or induction tool with wireline conveyed were run in early appraisal wells. . Meanwhile typical LWD bottom hole
assembly consists of gamma ray, resisitiviy, neutron, and density tool.
Two wells that exhibit swept zones are found in Gryphon and Harding which are the pilot hole of 9/18b-A30 in
GryphonIntroduce the wells and 9/23b-29A in Harding. Both wells were logged using LWD tool which consists of gamma
ray, resisitiviy, neutron, and density tool. The A30 pilot hole is a development well and reached TD on 17 September 2007
with the objective of Balder Massive Sandstone. It was logged using LWD tool and found the moving oil water contact at
5602 ft TVDSS, rising 129 ft from the original OWC at 5731 ft TVDSS. The apparent swept zone is clean high porosity sands
Fig. 4 Reservoir wettability data measured from various type of core plugs. Fresh state plugs show a variety of wettability state
from strongly oil wet to weakly water wet
Formatted: Not Highlight
Formatted: Normal, Left
Formatted: Font: (Default) Times NewRoman
Formatted: Normal, Left, Position:Horizontal: 1.83 cm, Relative to: Page,Vertical: 1.32 cm, Relative to:Paragraph, Height: Exactly 1.25 cm
Formatted: Font: (Default) Arial, 8 pt
Formatted: Position: Horizontal: 1.83cm, Relative to: Page, Vertical: 1.32cm, Relative to: Paragraph, Height:Exactly 1.25 cm
Formatted: Font: (Default) Arial, 8 pt
Formatted: Normal, Left
Formatted: Not Highlight
Formatted: Indent: First line: 0 cm
Formatted: Font: (Default) Arial, 8 pt
Formatted Table
Formatted: Font: (Default) Arial, 8 pt,Not Highlight
Formatted: Font: (Default) Arial, 8 pt,Not Highlight
Formatted: Font: (Default) Arial, 8 pt,Not Highlight
Formatted: Font: (Default) Arial, 8 pt,Not Highlight
Formatted: Font: (Default) Arial, 8 pt,Not Highlight
Formatted: Font: (Default) Arial, 8 pt,Not Highlight
Formatted: Font: (Default) Times NewRoman, Not Highlight
Formatted: Normal, Left
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: para, Indent: First line: 0.5 cm
6
with gamma ray reading around 20 GAPI. The average resistivity value over the swept zones is 0.6 ohm.m. The other well is
9/23b-A29 in Harding was drilled targeting the same Balder Massive Sandstone and found oil water contact at 5625 ft TVDSS
rising 179 ft from the original OWC at 5804 ft TVDSS.
Literature Review Sorw from Open Hole Log
The idea of determining Sorw from open hole log is to calculate saturation in a water-swept zone resulted from moving oil-
water contact. Wells are carefully selected for those which exhibit moving oil-water contact that is vertical wells or pilot holes.
These wells are expected to exhibit a clear contrast of saturation in the swept zones. Sorw calculation from open hole logs are
very sensitive to various element including the type of drilling mud, shale volume which resulted to porosity values, and a
number of electrical properties as constants in water saturation formequation. In order to produce a valid outcome, the result
from open hole logs is calibrated using core analysis data. Accurate calculation of water saturation from open hole logs in
swept zone is more difficult than in oil zone, as small amounts of measurement error have large effects at high Sw as found by
[Al-Sabea, [2004]. Accurate porosity, resistivity, and formformation water resistivity (Rw) is required, and also good
understanding of cementation factor exponent (m) and saturation exponent (n) for the respective formformation.
Sorw from Special Unsteady State Oil-water Relative Permeability Analysis Core Analysis
Unsteady state displacement method has been a preferred industrial standard for relative permeability measurement since it
is simpler and faster to be carried out as recommended by [Stiles, [2004]14
. And also the fact that In particular, imbibition
unsteady state methods physically mimics the displacement process in the reservoir whereas oil first saturates the reservoir and
followed by water as displacing fluids, and . And the fact that unsteady state method is conducted in a relatively higher rate
than steady state. In unsteady state method core are saturated with crude mineral oil up to initial water saturation (Swi) and
then brine is introduced. The measured oil and water rate are then taken for relative permeability using Johnson-Bossler-
Naumann (JBN) method as described by [Stiles [, 2004]. The test was carried out using unsteady state method by flooding
displacing refined mineral oil the plug with simulated formformation brine in constant flooding pressure at low rates using oil-
water viscosity ratio equal to 11:1.
Normally high viscosity mineral oil is used which leads to early breakthrough followed by two phase flow. The period of
two phase flow is controlled by the wetting state of the sample, at which strong oil wet condition will allow a longer period of
time as found by [Anderson [, 1987]. However, in a high oil-water viscosity ratio, the period of two phase flow is also
significant regardless the wetting state of the rock as observed by [Anderson [, 1987]. The possible weakness is the lack of oil
relative permeability data at high water saturation where the test is terminated which makes residual oil saturation may higher
than the actual value. Some authors [Cordiner, [1972],; Davies, [1993];, Hirasaki, [1996],; and Rathmell, [1973] 6, 7, 9, 13
suggest that centrifugation after unsteady state may define the extension of valid Kro curve from the high rate flood and to
diminish the capillary end effect. In a strongly water wet sample, most oil will be produced before the breakthrough with
minimum or zero oil production afterwards. When the test is conducted at favourable oil-water viscosity ratio, the plug will be
flushed down to irreducible water saturation at a short period of time as observed by [Anderson, [1987]. The opposite
phenomenon occurs in a strongly oil wet sample, when it takes a long period of two phase flow to flush the core down to
Swirr.
However, sSeveral considerations should be brought up into our attention before taking laboratory data for further analysis.
Inappropriate coring fluids, incorrect sample preservation, sample cleaning and drying, and use of refined oil might lead to
wettability alteration as shown by several authors [Anderson2, [1987]; Anderson
3, 1987; and Kennaird, [1988].
2, 3, 10. Result
should also be used in cautious way if the tests are conducted on individual short core plugs and at ambient conditions.
Conducting the test at low rates also potentially create capillary end effects especially in an intermediate wettability and high
permeability (>500 mD) samples [Stiles, 2004]14
. It is also often difficult to enforce a sufficient pressure differential across the
core in an unsteady state waterflood to reduce capillary forces without flood becoming unstable. This can be mitigated through
use of long composite core.
Refining the relative permeability curve is needed to extend the data beyond the saturation range achieved in the
laboratory. The value of Krw at Sor which is referred as Krw end point often used as an indication of the wettability of
rock/fluid system. Should the value of Sor be too high due to premature ending of the flood, the Krw end point will be too low.
These are undertaken by fitting the data into a curve generated from a power function of Corey exponent, and extend the curve
to the wider saturation range than one reported by the laboratory result.
Previous works by several authors [Davies, 1993; Kennaird, 1988; Rathmell, 1973] 7, 10, 13
shows that when the plug is
flooded at a higher rate with a higher terminal pressure differential, the flood would have proceeded to lower oil saturations.
Such a high rate is often referred as bump flood, and is conducted at the end of a conventional core floods experiment. The
work by Gauchet et.al, (1993) as cited by [Stiles, 2004]an author14 explains the decrease in the Sor values with an increase of
pressure differential of intermediate wettability sample. No effect was observed when the test was conducted on a strong
water-wet sample. And an increasing trend of Krw end-point was also observed with the increase of differential pressure
It is often reported that a test result from a single test might not present consistent data over the range of of saturations of
interest. And it is important to incorporate results from different test to define the entire relative permeability curve. The check
of Corey exponents should also be consistent with wettability measurement with the guidelines shown on the following table 5
which was cited from [Stiles, [2004].
Formatted: Head1
Formatted: Default Paragraph Font
Formatted: Head2, Indent: First line: 0 cm
Formatted: Not Superscript/ Subscript
7
Wettability Corey Exponent Krw End Point
No Nw
Strongly Water-Wet 2 to 3 4 to 6 0.1 to o.4
Mixed Wettability 3 to 5 2 to 4 0.5 to 0.9
Oil Wet 6 to 8 1.5 to 3 0.8 to 1.0
(Re-printed from Stiles [2004])
End-point value approaching or exceeding 1.0 may be the result of wettability of the core has been altered to oil wet by
inappropriate coring fluid i.e. oil base mud. Sor values obtained from different test procedure might give different results with
water flood test being the most affected by capillary end effect. Calculated water relative permeabilities which are too high
early in a water flood are one of the most common problems associated with unsteady state test.
The Kro curve can then be extended in the same way of Krw. The final oil saturations reported at the end of core floods are
often significantly higher than the true residual oil saturation for the rock as observed by [Stiles [, 2004]14
. This is often due to
the pressure differential across the core being insufficient to overcome the capillary pressure at lower oil saturations.
Data Screening
As laboratory works for core analysis studies were carried out by different vendors, the consistency of results become
questionable when laboratory techniques are not standardised. In the case of existing data, a validity check should be
conducted and any discrepancies should be identified. It is necessary to identify valid test results and select for representative
data among the vast amount of available data. The proposed method by [dDos Santos [, 1997]8 is to check if the experiment
followexperiments follow several conditions which are:
- The capillary number associated to the displacement should be lower than 10-5
- The end effect must be negligible.
- The displacement must not show gravity segregation.
Capillary number (Nc) is a function of fluid viscosity, oil-water interfacial tension and displacement rate., in which inIn
the reservoir this number should be in the range of of 10-7
or less because of low velocities. However, in the laboratory
experiments this number is often much higher because the displacement rates are higher than in the reservoir. The capillary
number is related to the immobile oil droplets in the end of core sample at the end of displacement process. This oil saturation
will become mobile when the “drag” force of water is larger than the trapping capillary pressure. The residual oil saturation
will be at maximum when the capillary number is smaller than 10-5
and below that number the oil droplets will start to be
mobile due to the “drag” force.
As oil-water displacement is a resultant of viscous and capillary force, the dispersion of the flood fronts is controlled by
capillary forces. When it is reduced the dispersion of the flood front is negligible and water saturation will change sharply
before and after the front which is normally called “piston like displacement”. It is a necessary condition for the conventional
Johnson-Bossler-Naumann (JBN) method to be applicable for relative permeability calculation. Having the flood front
dispersed, the variation of residual saturation behind the front will be more gradual and does not reflect the true residual oil
saturation. This phenomenon is defined by end effect number (Nend) which is a function of the distance or the length of the
core plugs, oil viscosity, permeability, porosity and the displacement rates. In order to have a “piston like displacement” the
end effect number should be less than 0.1.
Another screening criterion is to find whether the test result is affected by gravity segregation during the test. This is to
ensure that the pressure drop over the core due to viscous force must be larger than the hydrostatic pressure of water and oil.
But given the small size of of core plugs, this condition is practically always met. This phenomenon is defined by gravity
number (Ng) which is the function of oil and water density, displacement rate, sample dimension, permeability, and oil
viscosity.
Core Water Flood Test.
Core water flood experiments has a similar procedure to oil-water relative permeability experiments where core is saturated
by mineral oil and then flushed by water as displacing fluid at a constant pressure. Bland mineral oil is used to match 11:1
viscosity ratio to brine and the iIncremental flow of oil and water volumes areflows of oil and water volumes are recorded as a
function of time. The displacement is carried out at a low rate of 5cc/sec until until the water cuts exceed 99.9%. The oil
saturation at this point might be referred as residual oil saturation, and to overcome the capillary end effect, a final flush at
higher rate of 500cc/sec was conducted and it is referred as bump flood. New residual oil saturation then again measured
which normally gives lower residual oil saturation values.
Table 5 Values of Corey Exponent for Different Types of Wettability
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: Not Bold
Formatted: Centered
Formatted: Not Superscript/ Subscript
8
Core water flood experiments has a similar procedure to oil-water relative permeability experiments where core is saturated
by mineral oil and then flushed by water as displacing fluid at a constant pressure. Bland mineral oil is used to match 11:1
viscosity ratio to brine and the incremental flow of oil and water volumes are recorded as a function of time. The displacement
is carried out at a low rate of 5cc/sec until until the water cuts exceed 99.9%. The oil saturation at this point might be referred
as residual oil saturation, and to overcome the capillary end effect, a final flush at higher rate of 500cc/sec was conducted and
it is referred as bump flood. New residual oil saturation then again measured which normally gives lower residual oil
saturation values.
A previous study by [Wood [, 1991] 18
shows that residual oil saturation in mixed wettability reservoirs by water flood is
often a strong function of pore volumes (PV) of water injected. Previous works by several authors [Cordiner [, 1972];, Davies,
[1993],; and Rathmell [, 1973]6, 7, 13
shows that in a high permeability sample, residual saturation that obtained from water
flood experiments do not represent the real residual saturation even bump flood has been carried out. The reason is for a high
permeability rock, a core flood only apply small pressure drop across the core, which leaves behind unswept region within the
core plugs.
Another work by [Hirasaki [, 1996] 9 reported that the Sorw of mixed wet sandstone system is sometimes very low, e.g =
10%. It can be measured only if the duration of the experiment is long enough and the driving force for displacement (gravity
or pressure gradient) is large compared to the capillary pressure retaining the oil as a wetting phase end effect. Welge’s
integration of Buckley Leverett equations could show that how many pore volumes of throughput will be required to reduce oil
saturation close to the Sorw.
Methodology
The exercise is to determine and integrate Sorw values is conducted by calculating the value from the existing water-oil
relative permeability data, open hole log data, and core flood data. Water-oil permeability data is refined to extend laboratory
measured value and then reliable sample are selected by using a screening criteria as described in detail in the following
section. Sorw from open hole log data is calculated using Archie formula over the swept zone, and the method will be
described also in the following section.
To seeinvestigate the extends effects of the amount of water injected to the true residual saturation, the refined water-oil
data was analyzed using Buckley Leveret method was used s to calculate fractional flow of water in vertical displacement from
core data. An attempt is to create use reservoir simulation as a tool was conducted by creating a sector model to find the
impact of the number of pore volume water injected to Sor particularly in the case of moving oil water contact. The sector
model is taken from Gryphon full field model particularly in the area penetrated by well 9/18B-A30 where moving contact was
observed from the open hole logs.
Data mining on open hole well logs, Routine Core Analysis (RCAL) and Special Core Analysis (SCAL) report was
conducted for all the fields. Open hole logs data are focused on vertical well and pilot hole which most likely intersect the oil-
water contact.
Another attempt to replicate the result of Buckley Leverett analysis on the log data was made tTo see the correlation
between oil saturation and the amount of water which has swept at a particular depth on a log data,. This was done by adding
together the bulk volume water (BVW) value in the bottom-up direction which acts as the water injection, and are plot it with
against the corresponding oil saturation (So). The obtained Sorw data then reconciled to produce a new range of applicable
Sorw.
The updated Sorw values arewere then implemented to the existing reservoir simulation model, by re scaling the existing
relative permeability curve, to look at the impact of different Sor to ultimate recovery. The available Gryphon simulation
model treats the entire field (Gryphon, Maclure, Tullich and Harding) as a single and connected geobody.
Relative Permeability Curve Refinement
All oil-water relative permeability curves generated from laboratory experiments were should be refined using the
workflow mentioned in previous section. The purpose is to obtain representative values of end point Sor, and also to generate
Corey exponents for each curve for Buckley Leverett analysis later on. The following steps were proposed by Stiles [2004] to
refine water-oil relative permeability data. First step of refining relative permeability curve is to observe the curve shape where
smooth and monotonic curves should be noticed for a good quality relative permeability data as shown on figure 4(a). This
followed by plotting the curve in log-log graph where good quality data should give concave downward for both oil and water
curve as shown on figure 4(b). Next is to estimate the value of Krw end point by normalising the water curve (Swn) and
plotting the Swn over Krw from on a log-log scale. Valid data will yield straight line if the flood is stabilize and extrapolation
to the Swn equal to 1 (Sor) will yield an estimate to Krw end point as shown on figure 4(c). The value of Corey exponent for
Krw curve (Nw) can be calculated using the following equation.
end-point
w
log log
log 1.0 log
rw rw
wn
K KN
S
… ……..................................................................................................................…... (1)
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: English (U.K.)
Formatted: Font: Bold
Formatted: Indent: First line: 0 cm
9
Curve Refinement
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0 0.2 0.4 0.6 0.8 1.0
Sw
Kr
Krw
Kro
`
Curve Refinement
0.00
0.01
0.10
1.00
0.0 0.2 0.4 0.6 0.8 1.0Sw
Kr
Krw
Kro
`
Krw End Point
y = 0.61x1.70
R2 = 0.99
0.100
1.000
0.1000 1.0000Swn Refined
Krw
Lab
510
uo
cN
110Lu
o
k
endN
The resulting values of Nw are then plotted against water saturation and the stabilized values of Nw is taken as the reliable
value, with the same way was used to determine No as shown on figure 4(e). The Krw curve then could be refined by the
following equation.
The next step of refinement is to estimate Sor value and extending the Kro curve, which is conducted by normalising the
oil saturation using different values of assumed Sor and plotting the result versus Kro on a log-log plot as shown on figure
4(d). The value which yields a straight line is used as an estimate of Sor with the slope being Corey exponent to oil (No). Kro
curve then could be generated using the following power equation.
Different values of Sor are substituted to the Son equation above and the results plotted versus Kro. The value of Sor which
yields a straight line is then used as Sor as shown on figure 4(d). The plot of relative permeability in a log-log scale is useful to
construct smooth Kro curve at low water saturations where little data are often available from the laboratory measurement.
Having refined all the end-points and Corey exponents, a new set of curve could be generated and it is shown on figure 4(f).
Data Screening
Screening of valid laboratory results for oil-water relative permeability is conducted by calculating capillary number, end
effect number, and gravity number for each sample. The three constraints are defined by the inequalities below, and the range
of values for each parameter are summarised in table 6 as cited from Bona [2000].
This screening method largely pointed out that in the common industrial practice of relative permeability
determination by unsteady state method, capillary forces are neglected. This is true when the core sample is long enough, but
in the reality core plugs usually does not exceed 15-20 cm (6-8 in). The three criteria mentioned above will provide a validity
check to the routine JBN (Johnson-Bossler-Naumann) method to calculate relative permeability at given displacement rate and
core sample lengths in the laboratory.
(Re-produced from Bona [2000])
Table 6 Range of Values for Screening Criteria Capillary Number (Nc) End-effect Number (Nend) Gravity Number (Ng)
Min 1.80E-06 5.30E-03 1.60E-06
Max 1.00E-05 1.00E-01 1.00E-02
…..………… (5) .………… (6) 210
Luo
gDk
gN
.……………… (7)
end-pointwN
rw rw wnK K S ……....................................................................................................................….........….. (2)
1
1
w oron
wi or
S SS
S S
……………...………....……….
(443)
1
1
oN
w orro
wi or
S SK
S S
……………………..................……
(334)
Formatted: Indent: First line: 0 cm
Formatted: Normal, Tab stops: Not at 0 cm
Formatted: Font: Not Bold
Formatted: Position: Horizontal: 4.99cm, Relative to: Page, Vertical: 0.22cm, Relative to: Paragraph
Formatted: Space Before: 0 pt, After: 0 pt
Formatted: Indent: First line: 0 cm,Space Before: 0 pt, After: 0 pt
Formatted: Centered, Indent: Firstline: 0 cm, Space Before: 0 pt, After: 0 pt
10
Sro Determination
0.001
0.01
0.1
1
0.010.11Son
Kro
Sro 1
Sro2
Sro3
Corey End Points
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.00 0.20 0.40 0.60 0.80
Sw Refined
Nw
* an
d N
o*
Nw
No
Curve Refinement
0.0
0.2
0.4
0.6
0.8
1.0
0.0 0.2 0.4 0.6 0.8 1.0
Sw
Kr
Krw
Kro
Krw, ref.
Kro, ref.`
Open Hole Logs Analysis
After doing data mining on all available well log curves, there are two wells only which exhibit moving OWC. One well is
found in Gryphon which is well 9/18B-A30 and another one is found in North Harding which is well 9/23B-A29. Sorw values
calculated from these wells will be the basis of log-derived Sorw.
Porosity Model
Previous study shows that Balder Massive Sandstones is a clean formformation with very low shale volumes that makes
standard neutron and density data is valid for porosity calculation. Porosity in clean sands can be expressed as:
wWhere in this case PHI = PHIT = PHIE and equation (8) will subsequently be used for porosity calculation.
Water Saturation Calculation
Archie formequation for clean sand is applicable to calculate water saturation over the net interval in Balder
FormFormation. Water saturation is then calculated using the formequation below:
Fig.ure 3 Fig. 5 Relative pPermeability cCurve rRefinement wWork fFlow as suggested by Stiles [2004] from raw data
(a) (b) (c)
(d) (e) (f)
fma
bma
PHI ….........................................................................................................…………………….…..…….…… (8)
n
t
w
mwR
RaS
1
………………………….…..........................................................................................................……… (9)
Formatted: para1
Formatted: Position: Horizontal: 1.77cm, Relative to: Page, Vertical: 2.47cm, Relative to: Paragraph, Width:Exactly 17.09 cm
Field Code Changed
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: para1
Formatted: English (U.K.)
Formatted: Space Before: 0 pt, After: 0 pt
11
Electrical properties measurements on core sample were conducted at in-situ stress and salinity conditions using fresh state
plugs to determine cementation factor “m” and saturation exponent “n”. FormFormation resistivity factor (FRF) which
measured at overburden pressure is plot against porosity on a log-log scale giving the gradient of cementation factor.
Resisitivity indexSaturation exponent was measured during waterflood test (imbibitions process) and was obtained by taking
the slope of FormFormation Resisitivity Index (FRI) with fractional water saturation plotted on a log-log scale. Histogram of
m and n then constructed. Water reisitivity (Rw) value are obtained from the histogram of apparent water resistivity value
(Rwa) calculated from deep resistivity (Rt) using the following formequation
Sensitivity in Archie Equation
Archie equation is error prone since some of the parameters are directly measured and others are indirectly derived. To
capture the uncertainties in each Archie constant, a method to calculate partial error contribution of each parameter to water
saturation is used as observed by Chen [1986]4. The method is based on standard analysis of error, and using the variance of
each parameter to calculate the fractional error contribution denoted as Cxi. The associated formequations for each Archie
parameter are:
Standard deviation (σxi) of each variable is calculated by assuming some uncertainties which normally attributed in each
measurement or experiment to derive each parameter. The assumed uncertainty (± yi%) can be used to provide the best
estimate4 of ± σxi by taking the base case value Xi as the multiplier, which is normally the mean value.
Results Open Hole Log Result Analysis
Porosity
Log derived porosity was found to be in a good agreement with core porosity measured at in situ stress condition. The
calculated average porosity is in the range of 30-36% over the net sand. The comparison of log derived porosity superimposed
with core porosity is shown on the figure 5 from well 9/18B-11 as an example in which core porosity data is available. The
core porosity shown as black dots are in good agreement with PHI curve.Gamma ray curve on the gamma ray track also show
very clean sand interval at 22-25 GAPI.
Water Saturation
Electrical properties and water resistivity data are presented in histograms and are shown in Appendix III. The mode values
of saturation exponent and cementation factor histograms are 2.70 and 1.71 with standard deviation of 2.71 and 1.74
respectively. The cementation factor indicates the typical value of slightly cemented sands, which might be not so accurate for
Balder Sandstone which is found to be much unconsolidated. The standard deviation values will be used as an input for
sensitivity analysis later on. Apparent water resistivity histogram has the mode value of 0.062 ohm.m and standard deviation
of 0.332 ohm.m. Direct measurement on several formformation water samples give an average water resistivity of 0.108
ohm.m at 77 deg F or equivalent to 0.0616 ohm.m at reservoir temperature. Table 7 summarise the statistical data from Archie
parameters calculation.
The graphical results of the calculated water saturation for both well 9/18B-A30 and 9/23B-A29 are presented on figure 7
6(a) and (b) respectively. Most likely value is shown by blue curve on water saturation track and denoted as P50 water
saturation. The uncertainties in Archie parameter are captured by calculating the P90 and P10 values as shown by red and
green curves respectively. In the clean sandstone body found in well 9/23B-A29 of Harding, the P50 Sor is found in the range
of 20-25% which is gradually decreasing over depth. The lowest Sor found to be at the lowest depth and increasing upwards.
On the other hand, similar trend was not found in well 9/18B-A30 of Gryphon where the P50 Sor is found in the wider range
of 10-27%. The tabulated values of log derived Sorw are presented in table 9.
mPHIRtRwa …....……………………...........................................................................................................…… (10)
2
mC …..…………….………....................… (14)
…..…………...……...................…… (15)
…..…………….........................…… (16)
2
2
ln
ln
nn
mm
SwC
C
iixi Xy % …....…....................................................................................................................................……… (17)
2
2
2
RtC
RwC
aC
RtRt
RwRw
aa
………............................................………… (11)
…………........................................……… (12)
…………….….....................................…… (13)
Formatted: para
Formatted: English (U.K.)
Formatted: para
Formatted: para
Formatted: English (U.K.)
12
Water-Oil Relative Permeability Sor Histogram
0
1
2
3
4
5
6
7
00.
020.
040.
060.
08 0.1
0.12
0.14
0.16
0.18 0.
20.
220.
240.
260.
28 0.3
0.32
0.34
0.36
0.38 0.
4
Sor
Fre
qu
en
cy
All SCAL Data
Water-Oil Relative Permeability Histogram
0
1
2
3
00.
020.
040.
060.
08 0.1
0.12
0.14
0.16
0.18 0.
20.
220.
240.
260.
28 0.3
0.32
0.34
0.36
0.38
Sor
Fre
qu
en
cy
Validated SCAL Data
Core Analysis Result
Oil-Water Relative Permeability
Residual oil saturation from refined oil-water relative permeability curves are tabulated as a histogram in figure 6 (a).The
values range from the lowest of 10% to 40% at the highest with mode of the data at 20%. After applying the screening criteria
using as explained in the previous section, the number of samples was highly reduced and a new histogram of Sorw is
constructed as shown on figure 6(b). Given the small number of samples that follows the criteria, the range of Sorw is also
narrowed from the lowest of 16% to the highest of 31%.
Core Analysis Result
Dean Stark
Residual oil saturation from Dean Stark extraction method is presented as a histogram in Appendix 5. The histogram shows
that the Sor range from 5% to 98% with no obvious distribution is observed. The result becomes highly questionable as oil
saturation above 27% should have been mobile referring to the highest Sor from open hole log results. Core samples in which
Dean Stark analyses were conducted are taken from the oil zone which has not been flushed by moving oil water contact.
Therefore the oil saturation from Dean Stark becomes incomparable to the Sorw from oil-water displacement experiments in
SCAL. In this instance, only the lowest limit of residual oil saturation from Dean Stark method is taken as a reference which is
5 %.
Table 7 Archie Equation Parameters
Cementation
Factor (m) Saturation
Exponent (n) Apparent Water
Resistivity (Rwa)
Mode 1.71 2.70 0.062
Median 1.71 2.60 0.058
Average 2.19 2.58 0.072
P10 1.60 1.78 0.109
P50 1.71 2.60 0.040
P90 1.95 3.16 0.058
Std Deviation 1.74 2.71 0.332
Table 8 Uncertainties in Archie Parameters
m n Rwa Φ a Rt
Uncertainties (%) 5 5 5 10 0 5
Well Low Most Likely High Avg Φ
9/18B-A30 (Upper) 0.05 0.1 0.2 0.3
9/18B-A30 (Lower) 0.1 0.2 0.25 0.3
9/23B-A29 0.18 0.2 0.3 0.38
Table 9 Residual Saturation from Open Hole Log
Fig.ure 4 Fig. 6 Comparison of lLog and cCore pPorosity
Fig.ure 76 Sorw Histogram from Relative Permeability Analysis
(a) (b)
Formatted: Position: Horizontal: 8.56cm, Relative to: Page, Vertical: 0.31cm, Relative to: Paragraph
Formatted: Indent: First line: 0 cm
Formatted: Indent: First line: 0 cm
Formatted: Justified, Position:Horizontal: 1.4 cm, Relative to: Page,Vertical: 0.21 cm, Relative to:Paragraph
Field Code Changed
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Position: Horizontal: 6cm, Relative to: Page, Vertical: 2.17cm, Relative to: Paragraph
Formatted: English (U.S.)
13
Dean Stark Histogram
0
2
4
6
8
10
12
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
Sor (%)
Fre
qu
en
cy
0.00%
20.00%
40.00%
60.00%
80.00%
100.00%
120.00%Frequency
Cumulative %
Well Low Most Likely High Avg Φ
9/18B-A30 (Upper) 0.05 0.1 0.2 0.3
9/18B-A30 (Lower) 0.1 0.2 0.25 0.3
9/23B-A29 0.18 0.2 0.3 0.38
Fig.ure 5 Fig. 8 Residual oOil sSaturation in oOpen hHole lLog (a) (b)
Formatted: para1
Formatted: Keep with next, Position:Horizontal: 3.6 cm, Relative to: Page,Vertical: 0.03 cm, Relative to:Paragraph, Width: Exactly 14.18 cm
Field Code Changed
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: English (U.K.)
Formatted: para1
Formatted: English (U.K.)
Formatted: para1
14
Water-Oil Relative Permeability Sor Histogram
0
1
2
3
4
5
6
7
00.
020.
040.
060.
08 0.1
0.12
0.14
0.16
0.18 0.
20.
220.
240.
260.
28 0.3
0.32
0.34
0.36
0.38 0.
4
Sor
Fre
qu
en
cy
All SCAL Data
Water-Oil Relative Permeability Histogram
0
1
2
3
00.
020.
040.
060.
08 0.1
0.12
0.14
0.16
0.18 0.
20.
220.
240.
260.
28 0.3
0.32
0.34
0.36
0.38
Sor
Fre
qu
en
cy
Validated SCAL Data
Core Analysis Result
Dean Stark
Residual oil saturation from Dean Stark Extraction method is presented as a histogram in Appendix 5. The histogram
shows that the Sor range from 5% to 98% with no obvious distribution is observed. The result becomes highly questionable as
oil saturation above 27% should have been mobile referring to the highest Sor from open hole log results. Core samples in
which Dean Stark analyses were conducted are taken from the oil zone which has not been flushed by moving oil water
contact. Therefore the oil saturation from Dean Stark becomes incomparable to the Sorw resulted from oil-water displacement
experiments in SCAL. In this instance, only the lowest limit of residual oil saturation from Dean Stark method is taken as a
reference which is 5 %.
Oil-Wwater Relative Permeability
Residual oil saturation from refined oil-water relative permeability curves are tabulated as a histogram in . The obtained
Sorw then presented on figure 68 (a). covering all available data.
TThe Sorw values range from the lowest of 10% to 40% at the highest with mode of the data at 20%. After applying the
screening criteria using as explained in the previous sectionthe three constants, the number of samples was highly reduced and
a new histogram of Sorw is constructed as shown on figure 8(b). Given the small number of samples that follows the criteria,
the range of Sorw is also narrowed from the lowest of 16% to the highest of 31% with no apparent trend observed.
Core Water Flood
Core water flood data are presented Residual oil saturation values from core water flood data are obtained when the
effluent of displacement has reached 99.9% watercut. The saturation in the core plug was calculated by taking the ratio of the
volume of oil produced to the initial oil in place. Oil saturation is plotted against the pore volume of water injected and the
final saturation is achieved at the end of the test. From the plot on figure 879(a) and (b) it is shown that oil saturation is a
function of pore volume water injectedas a plot of oil saturation as a function the amount of water injected in PV.
Figure 7 Dean Stark Oil Sor Histogram
(a) (b)
Formatted: Indent: First line: 0 cm
Formatted: Space Before: 0 pt, After: 0 pt
Formatted: para1
Formatted: Indent: First line: 0 cm
Formatted: para1
Formatted: Indent: First line: 0 cm
15
Harding Core Flood
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30
Water Injected (PV)
So
(%
)
6E
13E
16E
42C
53C
47E
Gryphon Core Flood
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200
Water Injected (PV)
So
(%
)
13B 14A 11 1216 17 50 105106 108 109 143144 167 168 240V229VA 206VA 82V 87VA94VC 120VB 134VA 90VA162VA
(a) (b)
TThe plot on figure 879 shows that oil saturation decreases sharply showing that water breakthrough was achieved, and
subsequently two phases flow occur as more water is injected. Core floods data from Gryphon shows that oil saturation keeps
decreasing at approximately 140 PV of water injected. Most of the experiments were terminated when the oil volumecontent at
the core outlet is too low to be measured, although ever decreasing saturation is expected when the test is prolonged. Referring
to the wettability nature of Balder Sandstone which is indicated as a combination of intermediate, mixed, and neutral wet,
reduction in Sorw is expected in a prolonged test although the margin is not significant. Similar phenomenon is also observed
from Harding data which has similar porosity and permeability, but earlier termination of the test was observed after 20 PV of
water injected.
The residual oil saturation from core flood test ranges from 16% - 30% from Gryphon samples, and 10% - 30% from
Harding samples with one particular sample from Harding showing anomalously higher saturation of 40%., with anomalous
result then excluded from the majority of data. To see the extends of amount of water injected to the true residual saturation,
the refined water-oil data was analyzed using Buckley Leveret methods to calculate fractional flow of water in vertical
displacement. The calculated fractional flow then converted to oil saturation value and plotted over dimensionless water
injection in pore volume.
Buckley Leverett analysis shows that theoretical oil saturation will asymptotically reduced to residual saturation after being
swept by hundreds of pore volume of water. Figure 910 (a) shows the plot of theoretical oil saturation to the amount of pore
volume water injectedBuckley Leverett analysis from all relative permeability data set, and figure 910 (b) shows the result of
validated data set only. The replicated Buckley Leverett plot which is calculated from 9/23b-29A log data is superimposed
with relative permeability derived curve, and shown by the thick red line on figure 910 (b). The plot signifies a relationship
between log derived Sorw with the amount of PV water sweep, and current value of Sorw in the respective well is estimated to
be achieved after 30 PV of water swept.
,
and it indicates that the residual saturation obtained from core water flood test might be reduced to lower value when more
PV of water is injected.
An attempt to replicate the result of Buckley Leverett analysis on the log data was made to see the correlation between oil
saturation and the amount of water which has swept a particular depth. This was done by adding together the bulk volume
water (BVW) value in the bottom-up direction which act as the water injection, and plot it with the corresponding oil
saturation (So). This step was taken to the swept zone depth at which some amount of water has swept the oil as the oil-water
contact is rising. A well which shows clear swept zone over a clean interval, 9/23b-A29 was chosen to represent the modelling.
BVW is calculated by multiplying Sw and PHIE and added for each depth in PV unit.Taking the calculated value and
superimposed it with the same plot derived from the core Buckley Leverett analysis, the result shows similar trend and that
might indicate that oil saturation in this case Sor resulted from the vertical sweep is also a function of PV of water
encroachment.
16
Buckley Leverett Analysis
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 20 40 60 80 100
Dimensionless Water Injected (PV)
Oil
Sat
ura
tio
n (
PV
)
Buckley Leverett Analysis
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 100 200 300 400 500
Dimensionless Water Injected (PV)
Oil
Sa
tura
tio
n (
PV
)
Buckley Leverett Analysis
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 10 20 30 40 50 60 70 80 90 100
Dimensionless Water Injected (PV)
Oil
Sa
tura
tio
n (
PV
)
Another attempt is to create a sector model to find the impact of the number of pore volume water injected to Sor
particularly in the case of moving oil water contact. The sector model is taken from Gryphon full field model particularly in
the area penetrated by well 9/18B-A30 where moving contact was observed from the open hole logs.
Sector model simulation also identifies the relation of Sorw to the amount of water sweep. (a)
(b)
Figure 101 shows vertical permeability values in each grid cell from the X slice where in that region which ranges from
500 to 1800 mD with no major flow barrier that allows the moving OWC sweeps the oil zonecolumn. Figure 112 shows the
development of moving OWC and the gradual changes in oil saturation as OWC is advancing. Eventually oil saturation does
not dropped to the lowest saturation which makes the oil phase become immobile, but it slowly decreasing as more volume of
water swept a particular depth.
Fig.ure 7 Fig. 9 Sorw Histogram fromLaboratory cCore water fFlood eExperiments results
(a)(b)
Figure 7 Laboratory Core Water Flood Test
Result
Fig.ure 8 Fig. 10 Buckley LLeverett aAnalysis on rRefined wWater-oOil rRelative pPermeability dData from (a) all available data and (b) validated data from screening criteria superimposed with replicated log-derived curve
(a) (ba
)
(a) (b) Formatted: Position: Horizontal: 5.53cm, Relative to: Page, Vertical: 0.16cm, Relative to: Paragraph
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Indent: First line: 0 cm
Formatted: Indent: First line: 0.51cm, Width: Exactly 7.01 cm, Height:Exactly 1.92 cm
Formatted: Indent: Left: 0 cm, Firstline: 0.51 cm, Width: Exactly 7.01 cm,Height: Exactly 1.92 cm
Formatted: Bullets and Numbering
Formatted: Indent: First line: 0.51 cm
Formatted: Position: Horizontal: 1.63cm, Relative to: Page, Vertical: 0.18cm, Relative to: Paragraph, Width:Exactly 17.79 cm
Field Code Changed
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Indent: First line: 0.51cm, Tab stops: Not at 0 cm
Formatted: Font: (Default) Times NewRoman, 10 pt, Not Bold, English (U.S.)
Formatted: English (U.S.)
Formatted: Indent: First line: 0 cm,Tab stops: Not at 0 cm
Formatted: Indent: First line: 0.51cm, Tab stops: Not at 0 cm
17
Sor Reconciliation
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 1 2 3 4 5 6 7 8
Type of Test
Sor (Fract)
High Case Best Case Low Case
Implementation to Reservoir Simulation Model
Different ranges of residual oil saturation wereas obtained from different typesmeans of measurement, after previously
carefully selecting the available reliable data and refined it to produce a representative values. From every measurement, 3
values of Sor are generated giving the low case, best case, and high case estimate which the results are tabulated on figure 123.
Sor values from relative permeability end points, open hole logs from well 9/23B-A29, and core water flood analyses fall in
the range of 10%-30%, meanwhile open hole logs from lower layer of well 9/18B-A30, and Buckley Leverett analyses from
refined data has narrower range of 18%-25%. Open hole logs analysis from upper layer of well 9/18B-A30 resulted the range
of 5%-20%, and Dean Stark analysis only provides the low estimates of 5 % and the data is not very convincing due to the
wide spread of results. The final averaged low, best, and high case Sor are tabulated in table 10.
The updated Sorw values then implemented to existing reservoir simulation model to look at the impact of different Sor to
ultimate recovery. The available simulation model treats the entire field as one connected geobody where dynamics of oil and
gas production form one field is taken into account to the other fields. The new range of Sor was input to the history matched
water-oil relative permeability curves by changing the end-points to re-scale the curves. The existing data set relative
permeability curve used the in simulation model is shown on figure 143 and is where an equation was used to curve fit the data
to obtain a superimposed with the respective Corey model type equation. Having established the Corey exponent from original
curves, and the respective constants as shown in table 10. Figure 15 shows the new a re-scaled curves using the new range of
Sorw values is generated and presented in figure 143,. and itIt is obvious that lower Sorw end-point will drag the Kro curves
lower and vice versa. Thus the ultimate recovery is not only affected by the Sorw at the end of field life where oil phase
become immobile, but it also reducesd the overall relative permeability to oil from the beginning of production.
Cumulative oil production at 1 January 2018 is predicted from simulation model for each value of Sorw and the results are
summarised in table 11 and figure 15. The impact of different Sorw to the ultimate recovery to date is in the range of ±4% and
increasing to ±6% at 2018 which is considered on the low side.
Fig.ure 10 9 Fig. 11 Kv DistributiondDistributions in
sSector mModel
Fig. 12Sector model from Gryphon full field model showing decreasing oil saturation in the swept zones as oil water contact is increasing
Fig.ure 9 10 Sector mModel from Gryphon area full field model sShowing dDecreasing oOil
sSaturation in rRising oOil wWater cContact
No Type of Test
1 Dean Stark Data--
2 Relative Permeability End Point
3 Open Hole Logs 9/23B-29A
4 Open Hole Logs 9/18B-A30 Lower
5 Open Hole Logs 9/18B-A30 Upper
6 Buckley Leverett
7 Core Water Flood
No Type of Test
1 Dean Stark Data
2 Relative Permeability End Point
3 Open Hole Logs 9/23B-29A
4 Open Hole Logs 9/18B-A30 Lower
5 Open Hole Logs 9/18B-A30 Upper
6 Buckley Leverett
7 Core Water Flood
Fig.ure 12 Fig. 13 Sor Rreconciliation from different measurements
Formatted: Position: Horizontal: 1.72cm, Relative to: Page, Vertical: 0.81cm, Relative to: Paragraph
Field Code Changed
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Position: Horizontal: 6.56cm, Relative to: Page, Vertical: 0.41cm, Relative to: Paragraph, Width:Exactly 12.33 cm
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Position: Horizontal: 6.64cm, Relative to: Page, Vertical: 0.4 cm,Relative to: Paragraph, Width: Exactly 12.44 cm, Height: Exactly 0.8 cm
Formatted: Centered
Formatted: Highlight
Formatted: Font: (Default) Arial, 8 pt
Formatted Table
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Position: Horizontal: 1.93cm, Relative to: Page, Vertical: 0 cm,Relative to: Paragraph
Field Code Changed
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: 11 pt
Formatted: Centered
Formatted: Font: 9 pt, Not Bold
Formatted: Font: 9 pt
Formatted: Font: 8 pt, Not Bold
Formatted: Font: 8 pt
18
Water-Oil
Relative Permeability Model
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Sw
Kr
Krw
Kro
Krw, ref.
Kro, ref.`
Fig.ure 11 Fig. 14 Relative Permeability Data and Curve-fitted Corey Model
Fig.ure 13 Fig. 15 Relative Permeability Model for Flow Simulation
Table 10 Relative Permeability End Points for Sensitivity Analysis
End Points Sor Kro Krw Nw No Swi
Existing Simulation Model 0.24 0.709 0.185 1.95 2 0.08
Base Case Sor Model 0.2 0.709 0.185 1.95 2 0.08
Low Case Sor Model 0.1 0.709 0.185 1.95 2 0.08
High Case Sor Model 0.3 0.709 0.185 1.95 2 0.08
End Points Sor Kro Krw Nw No Swi
Existing Simulation Model 0.24 0.709 0.185 1.95 2 0.08
Base Case Sor Model 0.2 0.709 0.185 1.95 2 0.08
Low Case Sor Model 0.1 0.709 0.185 1.95 2 0.08
High Case Sor Model 0.3 0.709 0.185 1.95 2 0.08
Table 11 Ultimate Oil Recovery in Different Cases
Case Sorw % Change in EUR
Existing 0.24 0
Low 0.1 + 5.6%
Most Likely 0.2 + 1.4%
High 0.3 - 2.3%
Case Sorw Ultimate Recovery
Existing 0.24 213 MMSTB
Low 0.1 225 MMSTB
Most Likely 0.2 216 MMSTB
High 0.3 208 MMSTB
Water-Oil
Relative Permeability Model
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
0.00 0.20 0.40 0.60 0.80 1.00
Sw
Kr
Krw, ref. Kro, ref. Krw Base Case Kro Base Case Krw Low Case Kro Low Case Krw High Case Kro High Case
Water-Oil
Relative Permeability Model
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
0.00 0.20 0.40 0.60 0.80 1.00 Sw
Kr
Krw, ref. Kro, ref. Krw Base Case Kro Base Case Krw Low Case Kro Low Case Krw High Case Kro High Case
Formatted: Font: (Default) Arial, 8 pt
Formatted: Centered
Formatted: Position: Horizontal: 3.02cm, Relative to: Page, Vertical: 0.37cm, Relative to: Paragraph, Width:Exactly 6.43 cm, Height: Exactly 0.64cm
Field Code Changed
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Position: Horizontal: 10.45 cm, Relative to: Page, Vertical: 0.43 cm, Relative to: Paragraph, Width:Exactly 8.09 cm, Height: Exactly 0.38cm
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Indent: First line: 0 cm
Formatted: Font: (Default) Arial, 8 pt
Formatted Table
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Position: Horizontal: 5.48cm, Relative to: Page, Vertical: 0.38cm, Relative to: Paragraph, Width:Exactly 9.96 cm, Height: Exactly 0.43cm
Formatted: Font: 10 pt
Formatted: Font: 10 pt
Formatted: Font: 10 pt
Formatted: Font: 10 pt
Formatted: Font: 10 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: 9 pt, Not Bold
Formatted: Font: 9 pt
Formatted: Font: 9 pt, Not Bold
Formatted: Font: 9 pt
19
Partial Error Contribution
0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
20%
0.00 0.10 0.20 0.30 0.40
Porosity [v/v]
Fra
ctio
na
l E
rro
r C
on
trib
uti
on
[%]
Rt
Rw
Phi
m
n
m*
n*
DDiscussion Open Hole Log
Different trends were observed in open hole logs result, where 70 ft of swept zone in well 9/23B-29A clearly shows lower
saturation at the lowest depth where more PV of water has swept the reservoir, and gradually increasing upwards. The clean
sands with uniformform porosity penetrated by the well have allowed a single observable trend. On the other hand, visible
swept zone in well 9/18B-A30 are separated by a shale break with approximately 30 ft clean sections above and below the
shale. Although similar porosity values are observed in both section but the calculated Sor are different. The upper section
shows lower residual oil saturation compared to the lower section although obviously less water has swept the upper section.
These differences raise a question regarding the development of residual saturation, which not only depends on the amount of
water swept but might also depends to other variables such as petrophysical properties of the rock itself.
As Archie equation contains six variables, it is become important to know which constant is sensitive to contribute errors
to the calculated water waturation. Using the proposed method which 4 described in methodology sectionpreviously described,
partial error contribution of each constant can be calculated for different values of porosity which, and the plot is shown on
figure 146. At low porosity formformation, the cementation factor and saturation exponent contribute errors up to 15% and
decreases for higher porosity. In the case of Balder Massive Sandstone with average porosity above 30%, none of the constant
contributes to the error of water saturation. This concludes that saturation measurement by open hole logs is reliable for the
given formformation. However, it is important to be noticed that this result only applies in homogeneous low resistivity zone
which in this case is the resistivity of swept zone. In both wells, the swept zone resistivity is around 0.5 ohm.m where the oil
zone the resistivity could be as high as 300 ohm.m.
End Points Sor Kro Krw Nw No Swi
Existing Simulation Model 0.24 0.709 0.185 1.95 2 0.08
Base Case Sor Model 0.2 0.709 0.185 1.95 2 0.08
Low Case Sor Model 0.1 0.709 0.185 1.95 2 0.08
High Case Sor Model 0.3 0.709 0.185 1.95 2 0.08
Fig.ure 14 Fig. 16 Impact of dDifferent sSor to uUltimate oOil rRecovery
Formatted: para
Formatted: para1
Formatted: Position: Horizontal: 5.37cm, Relative to: Page, Vertical: 0.32cm, Relative to: Paragraph, Height:Exactly 0.45 cm
Field Code Changed
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: para1
Formatted: English (U.K.)
Formatted: Head1
Formatted: Not Superscript/ Subscript
Formatted: Not Superscript/ Subscript
20
Core Sor Relation to RQI
0
2
4
6
8
10
12
14
16
0 0.1 0.2 0.3 0.4 0.5
Sor (%)
RQ
I
Sor
Core Sor Relation to RQI
0
2
4
6
8
10
12
14
16
0 0.1 0.2 0.3 0.4 0.5
Sor (%)
RQ
I
Screened Data
Krw End Point Versus Permeability to Air
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
1 2001 4001 6001 8001 10001 12001 14001
Ka (mD)
Krw
En
d-P
oin
t
Krw End Point
Corey Exponent to Oil Versus Permeability to Oil
0
1
2
3
4
5
6
7
8
9
1 1001 2001 3001 4001 5001 6001 7001 8001 9001
Ko (mD)
No
Krw End Point
Wettability Effect To Sor
0
10
20
30
40
50
60
0 0.2 0.4 0.6 0.8 1
Wettability Index to Water
So
r (%
)
Clean State
Fresh State
Restored State
Poly. (Fresh State)
Swirr Relation To Sor
0
10
20
30
40
50
60
0 10 20 30 40 50
Swirr (%)
So
r (%
)
Fresh State
Restored State
Clean State
(a) (b) (c)
(d) (e) (f)
Wettability Effect To Sor
0
10
20
30
40
50
60
0 0.2 0.4 0.6 0.8 1
Wettability Index to Water
So
r (%
)
Clean State
Fresh State
Restored State
Poly. (Fresh State)
(fe)
Core AnalysisCore Data
In order to find the dependency of residual oil saturation to other reservoir rock properties, several cross plot have been
created to find the trend of Sor with rock quality and different petrophysical properties. A constant called Reservoir Quality
Index (RQI) which is the square root of permeability devided by porosity is used to describe the trend of Sor to the rock
quality. On figure 17618 (a) and (b) all Sor data and screened data from relative permeability end points are plotted against
RQI, but the no obvious trend is observed due to very high permeability samples shows high Sor. This is somewhat different to
earlier findings that residual oil saturation and true residual oil saturation are dependent on the rock type due to differences in
pore geometry7 as investigated by Chang [1988]. This is could be caused by insufficient pressure differential across the core
during the laboratory displacement that could not displace oil at lower oil saturation after breakthrough.
The best value to measure true residual oil saturation is by conducting centrifuge capillary pressure measurement carried
out on preserved core material using degassed reservoir oil, and ideally should apply the reservoir confining pressure as
observed by Chang [1988] and Kennaird [1988]7, 13
. In the centrifuge test, sufficient pressure drop could be exerted even to the
small and high permeability plugs. Since centrifuge oil-water capillary pressure measurement is not available in this study, the
resulted laboratory displacement for both relative permeability and core water flood which were conducted in low rates are
potentially affected by capillary end effect. While the capillary effects are reduced in the centrifuge test, they are still present
and can be important at low oil saturation. It is therefore important to to correct calculated Kro values at low oil saturation for
Fig.ure 15 Fig. 17 Partial Error Contribution from Archie ConstantSensitivity aAnalysis of aArchie eEquation
Fig.ure 168 Fig. 18 Effect of pPetrophysical pProperties to SsSor and CcCorey eExponents
Formatted: Space Before: 0 pt, After: 0 pt
Formatted: Keep with next, Position:Horizontal: 5.42 cm, Relative to: Page,Vertical: 0.13 cm, Relative to:Paragraph, Height: Exactly 0.5 cm
Field Code Changed
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Space Before: 0 pt, After: 0 pt
Formatted: English (U.K.)
Formatted: Head2, Space Before: 0pt, After: 0 pt
Field Code Changed
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
Formatted: Font: (Default) Arial, 8 pt
21
the capillary end effects using result from the centrifuge capillary pressure measurement. Valid Kr curve should resemble
concave downward when plotted on log-log scale.
Unsteady state method has some drawbacks that could lead to inaccurate measurement of Sor. The early breakthrough
might be caused by water fingering since the mobility ratio of oil and water is high, which was attempted to be solved by low
rates displacement. However, low rates displacement will lead to severe end capillary end effect that holds much of the oil at
the end of the core sample since insufficient pressure differential is not achieved to mobilize oil. Another thing associated with
unsteady state method is there is no adequate capillary pressure to stabilise the flood front, which lead non-uniformfrom Sor
behind the flood front. This phenomenon will make average Sor across the core plug become inaccurate. To overcome
capillary end effect a higher rate displacement should be taken, and longer core sample should be used so that flood front
stability could be achieved using lower oil-water mobility ratio. Lower mobility ratio could also avoid early breakthrough and
water fingering.
The use of refined mineral oil also affected the quality of measurement since native wettability of the core has been altered.
Normally the mineral oil used for flushing does not alter the core wettability as they are non-polar and does not contain
surfactant as observed by [Kennaird et.al, [1988]. Many of the problems surrounding oil-water relative permeability are
associated with wettability. Much of the data are invalid as a result of the problem of wettability and capillary pressure.
Wettability is a subject of alteration as a result of inappropriate coring fluid, improper core preservation, incorrect core
handling, and unrepresentative test condition.To investigate the wettability effect to Sor, a cross plot of AMOTTAmott
wettability index to water and Sor was constructed and shown on figure 157 (fe). It appears that most of the data fall in the
both ends of wettability index, which are 0 and 1. The core sample becomes less water wet when the index goes to 0 and
becomes more water wet when it goes to 1. No specific trend observed from the wettability and Sor cross plot where all the
fresh state data tend to scatter. However, the plot shows that cleaned state plugs tend to become more water wet, which is the
case when the residual crude was successfully extracted from the plugs. Meanwhile restored state plugs tend to become more
oil wet as due to the ageing process.
Corey exponents to oil (No) from relative permeability data indicates that the samples taken for analysis are mostly strong
water wet following the criteria of wettability on table 5 where majority of the values are in the range 1 to 3. On the other
hand, Krw end points give a more moderate result where the values spread in the range of 0.1 to 0.7 which indicate mixture
between strongly water wet and mixed wet rocks. The tendency of being more water wet rocks explains that the observed Sor
values are on the high side, since previous author indicates that the Sor reached a minimum value when the core sample
exhibited neutral mixed wet as investigated by [Conti, [2004]5. Neutral wettability is defined as a wettability state which is
neither water-wet nor oil-wet. To minimize the uncertainty in predicting effective residual saturation in mixed wettability
reservoirs it is necessary to consider competing effect of relative permeability, gravity forces, and imbibition capillary pressure
In core water floods experiments, a strongly water rocks are characterized by small or zero production after breakthrough,
where the residual oil in strongly water wet rocks reside as discrete, discontinuous droplets surrounded by water as concluded
by 6 [Rathmell [1973]]. While the residual oil in strongly oil wet is continuous phase occupying the pore surfaces. For the
reservoirs considered in this study, no difference in residual oil saturation was observed between the fresh and the restored
state waterfloods. The decreasing oil saturation as a function of PV of water swept which observed in the simulation result
aligned with a previous work by [Anderson] [1987] which shows that Sor is related to the throughput for mixed-wet cores. In
mixed wettability systems, the relative permeability curves allow significant oil production after water breakthrough, with oil
draining from pores as a continuous wetting phase. A cross plot between Sor and irreducible water saturation (Swirr) generally
shows that Sor decreases as Swirr increases. In a water wet rock, water act as a continuous phase which attached to the rock
surface which makes Swirr becomes high, and similarly in oil wet rock.
Summary and conclusions
Unsteady state relative permeability data potentially affected by end effect and capillary effect
ROS in Gryphon Area is a function of PV water swept due to the intermediate and mixed wettability state of the rock
The recommended ROS in Gryphon Area is 10%, 20% and 30% for low, most likely and high case.
True oil saturation is the minimum oil saturation that can be achieved under the combined viscous, capillary, and
gravitational forces.
Unsteady state method mimics the displacement in reservoir condition in which oil as a displaced fluid and water as
displacing fluid with single phase oil flow followed by two phase flow.
Residual oil saturation from water oil relative permeability test should be refined to extend the Kro curve which could
not be achieved during laboratory test.
Laboratory data should be investigated to exclude unreliable result and
The high apparent residual oil saturations at low flooding rates due to capillary effects are an example of an invalid
result. Such invalid data are to be disregarded and not included in the reconciliation process.
For a typical water-wet or mixed wet type rock, the an accurate residual oil saturation measurement could be achived
is defined by the oil-water imbibition capillary pressure curveexperiment. However this method is not applicable for Balder
Massive Sandstone due to unconsolidated nature of the formation.
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Font: Times New Roman,Not Bold
Formatted: Bulleted + Level: 1 +Aligned at: 0.63 cm + Indent at: 1.27cm
Formatted: Bulleted + Level: 1 +Aligned at: 0.63 cm + Indent at: 1.27cm
Formatted: Indent: First line: 0.5 cm
22
(m)diameter Sample :
)(m/sconstant Gravity :
)(kg/m differencedensity oil water :
(m)length Sample : L
(%)Porosity :
)m / (mDty Permeabili :
(N/m) tension linterfacia oil- Water:
(m/sec)ity arcy velocD' :u
(Pa.s) viscosityOil :
2
3
2
D
g
k
(ohm.m)ty Resisitivi Water : Rw
(ohm.m)y resistivit True :Rt
(%) saturation Water : Sw
exponent Saturation :n
factorn Cementatio : m
factor Tortuosity : a
xiofon contributierror Fractional : C
valuecase Base : X
(%)y uncertaint Assumed :y
xi veriableofdeviation Standard :
xi
i
i
xi
number Capillary : Nc
(ohm.m)ty Resisitivi Water : Rw
(ohm.m)y resistivit True :Rt
(gr/cc)density Fluid: f
(gr/cc)density Bulk : b
(gr/cc)density matrix : ma
(%) volumeShale :Vsh
(%)porosity Total : PHIT
(%)porosity Effective : PHIE
(ohm.m)y resistivitater Apparent w : Rwa
oil ty topermeabili Relative : Kro
numberGravity : Ng
number effect End : Nend
(%) water tosaturation oil Residual : Sorw
(%) saturation water Initial : Swi
waterty topermeabili Relative : Krw
wateroexponent tCorey : Nw
oil oexponent tCorey : No
saturation oil Normalised :Son
Residual oil saturation could also be calculated from resisitivity data from swept zones. However an accurate
estimation of Archie constant is important as saturation calculation in swept zone is very sensitive.The sensitivity analysis
shows that the Archie equation is robust at the condition of the swept zone. An accurate true resistivity value could be
obtained from induction log which is accurate at low resistivity.
In Balder Massive Sandstone, residual oil saturation is a function of pore volume of water sweep shown by core water
flood data and reservoir simulation. In this case the further advancing of oil water contact will lead to lower Sor.
The average residual oil saturation for grater Gryphon Area is 10%, 20%, and 30% for low case, most likely case, and
high case respectively.
The change in Sor will re-scale the oil-water relative permeability data set, which at the end effecting the field
production profile.
Wettability in Balder Massive Sandstone are varies from strong oil wet to mixed wet which observed from AMMOTT
wettability data and Corey exponent values.
For high porosity reservoir, none of the Archie parameter becomes dominant as a source of error in water saturation
calculation.
The new range of ROS will change the ultimate recovery from -2% to +6%
Recommendations
The recommended practice is to conduct centrifuge at the end of flood experiments, since centrifuge could exert sufficient
pressure drop across the core. It is reported that residual oil saturation measured from centrifuge tests are lower than those
determined by coreflood tests. And it is essential to take residual oil saturation from oil-water imbibitionwaterflood capillary
pressure measurement to define oil saturation end points beyond the corefloods.
Results form flooding involving flushing with large number of pore volumes of water which do not use water saturated gas
can result in artificially low residual saturation due to stripping of light ends. First step in the use of oil-water displacement
data is to gain understanding of the history of the core material used in the test, the type of test conducted, and the laboratory
procedure and conditioned used. The inaccuracies associated with flooding small core plugs and to problem associated with
capillary effects require laboratory results to be refined before being used further.It also recommended taking core sample in
the swept zone and measuring the saturation to get the actual Sorw at reservoir condition.
Check of consistency from the data integration can be conducted by observing Sor values which should be decreasing from
reservoir condition waterflood, centrifuge kro, and centrifuge Pc respectively. The Sor resulted then decreases in for centrifuge
Kro test and centrifuge Pc test respectively.
Although much affected by capillary end effects, true residual saturation might be achieved from laboratory water flood at
favourable oil-water viscosity ratio. An example case is in a low permeability, strongly water wet rocks that is water flooded
using low viscosity oil and with numerous pore volume throughput. Data from long, composite core are more reliable in doing
this as capillary pressure effect is reduced.
Acknowledgements I wish to express my gratitude to Maersk Oil North Sea UK Limited for the opportunity to carry out my MSc thesis. Most
appreciation goes for my supervisor Fabrizio Conti and Stephen Milner, everybody in Petroleum Engineering Department
particularly in Reservoir Operation Group. Special appreciation is dedicated for Gabriel Marcas and Ritesh Kumar from
Mature Field Studies team for insightful discussion and assistance with Eclipse software. I would also like to thank my
supervisor and colleagues at Imperial College for the support and enjoyable time during the MSc study.
Nomenclatures
Formatted: Font: Times New Roman,Not Bold
Formatted: Indent: Left: 0.5 cm, Firstline: 0.5 cm
Formatted: Bulleted + Level: 1 +Aligned at: 0.63 cm + Indent at: 1.27cm
Formatted: Font: Times New Roman
Formatted: para1
23
Formatted: para1, Tab stops: 6.61cm, Left
Formatted: para1
Formatted: Head1
24
References
1. Al-Sabea, Salem, Bean, Clarke & Crowe, John. (2004) Residual Oil Saturation Analysis of The Burgan FormFromation in
the Greater Burgan Field, Kuwait. Abu Dhabi International Conference and Exhibition. Abu Dhabi, United Arab Emirates,
Society of Petroleum Engineers.
2. Anderson, W. G. (1987) Wettability Literature Survey-Part 6: The Effects of Wettability on Waterflooding. SPE Journal of
Petroleum Technology, 39 (12), 1605-1622.
3. Anderson, William G. (1987) Wettability Literature Survey Part 5: The Effects of Wettability on Relative Permeability.
SPE Journal of Petroleum Technology, 39 (11), 1453-1468.
4. Anderson, William G. (1986) Wettability Literature Survey-Part 3: The Effects of Wettability on the Electrical Properties
of Porous Media. SPE Journal of Petroleum Technology, 38 (12), 1371-1378.
3.5. Chang, M. M., Maerefat, N. L., Tomutsa, L. & Honarpour, M. M. (1988) Evaluation and Comparison of Residual Oil
Saturation Determination Techniques. SPE Fromation Evaluation, 3 (1), 251-262.
4.6. Chen, H. C. & Fang, J. H. (1986) Sensitivity Analysis of The Parameters In Archie''s Water Saturation Equation.
(LOGANAL).
5.7. Conti, F. & Bona, N. (2004) EVALUATION OF RESIDUAL OIL SATURATION IN THE BALMORAL FIELD
(UKCS). SPWLA 45th Annual Logging Symposium. , Society of Petrophysicists & Well Log Analysts.
6.8. Cordiner, F. S., Gordon, D. T. & Jargon, J. R. (1972) Determination of Residual Oil Saturation AfterAfter
Waterflooding. SPE Improved Oil Recovery Symposium. Tulsa, Oklahoma, 1972 Copyright 1972 American Institute of
Mining, Metallurgical, and Petroleum Engineers, Inc.
7.9. Davies, G. W., Gamble, I. J. A. & Heaviside, John. (1993) Field-Wide Variations in Residual Oil Saturation in a North
Sea Sandstone Reservoir. SPE Advanced Technology Series, 1 (1), 180-187.
8.10. dos Santos, Renato L. A., Bedrikovetsky, P. & Holleben, Carlos R. (1997) Optimal Design and Planning for Laboratory
Corefloods. Latin American and Caribbean Petroleum Engineering Conference. Rio de Janeiro, Brazil, 1997 Copyright
1997, Society of Petroleum Engineers, Inc.
9.11. Hirasaki, G. J. (1996) Dependence of Waterflood Remaining Oil Saturation on Relative Permeability, Capillary
Pressure, and Reservoir Parameters in Mixed-Wet Turbidite Sands. SPE Reservoir Engineering, 11 (2), 87-92.
10.12. Kennaird, T. (1988) Residual Oil Saturations Determined by Core Analysis. Offshore South East Asia Show.
Singapore, 1988. Society of Petroleum Engineers Inc.
11.13. Purvis, K., Kao, J., Flanagan K., Henderson, J. & Duranti, D.(2002) Complex Reservoir Geometries in a Deepwater
Classic Sequence, Gryphon Field, UKCS: Injection Structures, Geological Modelling, and Reservoir Simulation. Journal of
Marine and Petroleum Geology. Elsevier Science.
12.14. Newman, M. St. J, M. L. Reeder, A. H. W. Woodruff, and I. R. Hatton. (1993) The Geology of the Gryphon Oil Field.
Petroleum Geology of west Europe: Proceedings of the 4th
Conference. The Geological Society, London, pp 123-133.
13.15. Rathmell, J. J., Braun, P. H. & Perkins, T. K. (1973) Reservoir Waterflood Residual Oil Saturation from Laboratory
Tests. SPE Journal of Petroleum Technology, 25 (2), 175-185.
14.16. Stiles, J. (20041995) Relative Permeability: It’s Use and Misuse in Reservoir Engineering. ENI In-house training.
Milan, Section 5, p 7-11.
15.17. Strange, L. K. & Baldwin, W. F. (1972) Core and Log Determination of Residual Oil After Waterflooding - Two Case
Histories. SPE Improved Oil Recovery Symposium. Tulsa, Oklahoma, 1972 Copyright 1972 American Institute of Mining,
Metallurgical, and Petroleum Engineers, Inc.
16.18. Syed, E. U., Salaita, G. N. & McCaffery, F. G. (1991) Determination of Residual Oil Saturation From Time-Lapse
Pulsed Neutron Capture Logs in a Large Sandstone Reservoir. Middle East Oil Show. Bahrain, 1991.
17.19. Valenti, Nick P., Valenti, R. M. & Koederitz, L. F. (2002) A Unified Theory on Residual Oil Saturation and Irreducible
Water Saturation. SPE Annual Technical Conference and Exhibition. San Antonio, Texas, 2002,. Society of Petroleum
Engineers Inc.
18.20. Wood, A. R., Wilcox, T. C., MacDonald, D. G., Flynn, J. J. & Angert, P. F. (1991) Determining Effective Residual Oil
Saturation for Mixed Wettability Reservoirs: Endicott Field, Alaska. SPE Annual Technical Conference and Exhibition.
Dallas, Texas, 1991 Copyright 1991, Society of Petroleum Engineers, Inc.
Formatted: Bullets and Numbering
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review1: Critical Literature Review 1
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
APPENDIX 1: APPENDIX - 1 Critical Literature Review
SPE
Paper No
Year Title Authors Contribution
88628718
2
200419
77
Residual Oil
Saturation Analysis of
The Burgan Fromation in
the Greater Burgan Field,
Kuwait.HOW SHOULD
WE MEASURE
RESIDUAL-OIL
SATURATION?
Al-Sabea,
Salem, Bean,
Clarke & Crowe,
John R. E. Wyman
This paper gives an example of
integrated residual oil saturation with the
case study of Greater Burgan Field in
Kuwait. The paper describe how historical
Pulse Neutron Capture log data could be
used to monitor the decreasing residual oil
saturation over time and the possibility of
variation in residual saturation in spatial
point of view.
One of the very first paper that
comprehensively describe and compare
various methods of measuring residual oil
saturation, by open hole log, cased hole log,
core analysis, tracer test, and reservoir
performance
3791 1972 Determination of
Residual Oil Saturation
After Water flooding
F. S. Cordiner,
D. T. Gordon and J.
R. Jargon,
Members AIME,
Marathon Oil Co
The very first paper that includes
pressure transient test as a tool to measure
residual oil saturation. Pressure transient test
tells the in-situ parameter such as effective
permeability and total compressibility. Later
on compressibility value indicates that gas
saturation remaining after waterflooding is
essentially zero
14887 1988 Evaluation and
Comparison of Residual
Oil Saturation
Determination
Techniques
Chang,M.M.;
Maerefat,N.L.;
Tomutsa,L.;
Honarpour,M.M.
This paper compares the various method
for residual oil saturation (ROS) for both
single well measurement and inter-well
measurement. It also presents a screening
criteria to select the best method under
certain wellbore and reservoir conditions
and present the results in statistical approach
19851 1993 Field Wide Variations
in Residual Oil Saturation
in a Sea Sandstone
Reservoir
Davies,G.W.;
Gamble,I.J.A.;
Heaviside,John
The paper explain the work of extensive
coreflood analysis from Sea sandstone
reservoir to provide reservoir wide
description.Various factors are investigated
using more than 200 samples. It is also
explains ROS distribution in spatial
perspective
30763 1996 Dependence of
Waterflood Remaining
Oil Saturation on Relative
Permeability,
Capillary Pressure, and
Reservoir Parameters in
Mixed Wet Turbidite
Sands
G. J. Hirasaki Describe the dependencies of residual oil
saturation (ROS) on relative permeability,
capillary pressure, and reservoir parameters.
The author work with a core sampe of
Turbidite sandstone reservoir. It focus on
swept region after waterflooding in water
wet and mixed wet system.
Formatted: Heading 1, Outlinenumbered + Level: 1 + NumberingStyle: 1, 2, 3, … + Start at: 1 +Alignment: Left + Aligned at: 0 cm +Tab after: 0 cm + Indent at: 0 cm
Formatted
2
Formatted: Right
Formatted: Font: Times New Roman,10 pt
Formatted: Font: Times New Roman,10 pt
16471123
923
198720
09
Wettability Literature
Survey-Part 6: The
Effects of Wettability on
Waterflooding Harding
Central—Achieving 74%
Recovery
Anderson, W.
G. P. Zhang and S.
Green
The paper is a comprehensive literature
survey on the effect of wettability to
waterflooding. The author compiled and
reviewed various core water flood
experiments and observes the impact of
changing wettability to waterflood
behaviour. Different wettability state
including water wet, oil wet and mixed wet
are discussed and compared to make clear
understanding on how different wetting state
could affect oil recovery.
The paper presents the success story of
Harding field reservoir management to
achieve high recovery factor
SPWLA
1986-
vXXVIIn5a3
1986 Sensitivity Analysis of
The Parameters In
Archie''s Water Saturation
Equation
Chen, H. C. &
Fang, J. H.
The paper provide a full sensitivity analysis
of the Archie water saturation equation,
assuming all six variables in the equatuion
to be error prone. The analysis was
performed in two models, (1) Equal
uncertainty and (2) unequal uncertainty. The
method proposed in the paper enables us to
quantify the error contribution of each
parameter. Sensitivity analysis become
important when the measurement of each
Archie parameter are not always accurate
and highly depends on the measurement and
interpretation technique.
SPWLA
2004-UUU
2004 EVALUATION OF
RESIDUAL OIL
SATURATION IN THE
BALMORAL FIELD
(UKCS)
Conti, F. &
Bona, N.
The paper provide of a case study for
residual oil calculation in Balmoral Field in
the UK North Sea using integrated core and
log analysis in the swept zone. The author
shows that not all the laboratory analysis
result is valid to be taken as a reference for
Sor study due to the associated uncertainty
from laboratory procedure and sample
condition.
39038 1997 Optimal Design and
Planning for Laboratory
Corefloods.
dos Santos,
Renato L. A.,
Bedrikovetsky, P.
& Holleben, Carlos
R.
The paper provides a method to quantify
different effect from laboratory experiments
in core water flood study. The method
proposed by the paper could be used for
planning a core water flood test to get a
reliable result.
17686 1988 Residual Oil
Saturations Determined
by Core Analysis
Kennaird, T. The paper discussed the result of
laboratory oil displacement experiments
using water and gas which conducted for
different purposes such as flood analysis
and relative permeability measurement for
various lithologies. The experiments were
conducted in different conditions such as
steady state, unsteady state, and centrifuge
at both reservoir and ambient temperature.
Formatted: Indent: First line: 0 cm
Formatted: English (U.K.)
Formatted: English (U.K.)
Formatted: Spanish (Venezuela)
Formatted: English (U.K.)
Formatted: English (U.K.)
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review1: Critical Literature Review 3
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
3785 1973 Reservoir Waterflood
Residual Oil Saturation
from Laboratory Tests
Rathmell, J. J.,
Braun, P. H. &
Perkins, T. K.
The paper presents the results of
theoretical and experimental study of
laboratory waterflood and core saturation
data which was obtained using water based
mud. The paper used previously published
information and its own experimental result.
3786 1972 Core and Log
Determination of
Residual Oil After
Waterflooding - Two
Case Histories.
Strange, L. K.
& Baldwin, W. F.
This is a case study of two fields under
waterflood which is assessed for tertiary
recovery. The method of determining
residual oil saturation comes from core and
log analysis. The paper investigate the effect
of mobile oil and water which lead to
flushing during coring operation which lead
the measurement become invalid.
3795 1991 Determination of
Residual Oil Saturation
From Time-Lapse Pulsed
Neutron Capture Logs in
a Large Sandstone
Reservoir.
Syed, E. U.,
Salaita, G. N. &
McCaffery, F. G.
The paper shows the utilization of
Pulsed Neutron Logs to investigate the
relation of residual oil saturation to the
amount of water sweep in the reservoir. The
in situ measurement provides a reliable
result since it is free from potential error
during the laboratory experiments.
77545 2002 A Unified Theory on
Residual Oil Saturation
and Irreducible Water
Saturation.
Valenti, Nick
P., Valenti, R. M.
& Koederitz, L. F.
The paper pointed out several classic
assumptions used in approximating
reservoir recovery in a small reservoir
which is no longer applicable when is used
in bigger reservoir. The unified theory of
residual saturation provides a general
approach for different type of reservoirs.
22903-
MS
1991 Determining Effective
Residual Oil Saturation
for Mixed Wettability
Reservoirs: Endicott
Field, Alaska.
Wood, A. R.,
Wilcox, T. C.,
MacDonald, D. G.,
Flynn, J. J. &
Angert, P. F.
The paper explains the significance of
mixed wettability to effective water
saturation, in which the value is a function
of the amount of PV of water injected.
Formatted: Font: 10 pt
Formatted: Indent: Left: 0 cm, Right: -0.04 cm, Tab stops: 6.33 cm, Left
Formatted: English (U.K.)
4
Formatted: Right
Formatted: Font: Times New Roman,10 pt
Formatted: Font: Times New Roman,10 pt
A1.1 SPE 3791 - DETERMINATION OF RESIDUAL OIL SATURATION AFTER WATER FLOODING
Authors : F. S. Cordiner, D. T. Gordon and J. R. Jargon, Members AIME, Marathon Oil Co
Contribution:
The first paper that includes pressure transient test as a tool to measure residual oil saturation.
Pressure transient test tells the in-situ parameter such as effective permeability and total
compressibility. Later on compressibility value indicates that gas saturation remaining after
waterflooding is essentially zero
Objective of Paper:
This paper illustrates the use of several independent testing and calculational procedures for
determining residual hydrocarbon saturations remaining in a reservoir after waterflooding. These
methods consist of material balance calculations, analysis of well test data, pressure transient
testing, core analyses, and borehole log calculations.
Methodology used:
Test case was carried out using data from two Pennsylvanian and Devonian age sandstone
reservoirs in Illinois, USA. Both fields undergone 5 spot-10 acre spacing waterflood. Core data,
well log data and reservoir performance data as well as pressure transient test data were utilized
to calculate ROS in different methods
Conclusion reached:
Good agreement was obtained for values of water saturation after waterfloods from several
independent methods. Relative permeability data are important to analysis technique, where
laboratory derived kr should be carefully validated. Field case show that waterflood performance
tends to verify laboratory Kr as well as indicates values of Sor. A comprehensive approach using
all tools available resulted in satisfactory answer
Comments:
Although good agreement was achieved but this paper does not describe uncertainties in each
measurement which eventually should be included to reflect tools limitation.
Formatted: Font: 12 pt
Formatted: Heading 2, Indent:Hanging: 0.52 cm
Formatted: Font: 12 pt
Formatted: Font: 12 pt, Bold
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt, Bold
Formatted: Font: 12 pt
Formatted: Font: 12 pt, Bold
Formatted: Font: 12 pt
Formatted: Font: 12 pt, Bold
Formatted: Font: 12 pt
Formatted: Font: 12 pt
Formatted: Font: 12 pt, Bold
Formatted: Font: 12 pt
Formatted: Font: 12 pt, Bold
Formatted: Font: 12 pt
Formatted: Heading 2, Indent: Left: 1cm, Space Before: 0 pt, After: 0 pt,Tab stops: 1 cm, List tab + 1.5 cm,Left
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review1: Critical Literature Review 5
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
A1.2 SPE 14887 - EVALUATION AND COMPARISON OF RESIDUAL OIL SATURATION
DETERMINATION TECHNIQUES
Authors: Chang,M.M.; Maerefat,N.L.; Tomutsa,L.; Honarpour,M.M.
Contribution:
This paper compares the various method for residual oil saturation (ROS) for both single well
measurement and inter-well measurement. It also presents a screening criteria to select the best
method under certain wellbore and reservoir conditions and present the results in statistical
approach
Objective of Paper:
A brief review of available ROS tachnique is presented indicating advantages, limitations,
problems, and possible improvement of each techniques. Advantages and disadvantages are
summarized, and screening criteria to select the best method is presented. The paper also
presents ROS vertical profiles to eliminate ROS variations resulting from formation depths. The
vertical profiles based on ROS zoning and foot-by-foot measurements were studied to provide
more "resolution" for comparisons. The results show that discrepancies in measurement methods
are more pronounced when vertical profiles are divided into different zones. This could mean
that the discrepancies are much greater for some zones than for others. This approach offers the
possibility of studying ROS-method discrepancies as a function of different ROS values.
Methodology used:
The paper compares data from 89 measurements in 57 sandstones reservoirs and 18
measurement in 4 carbonates reservoirs from Interstate Oil Compact Comission (IOCC) in
Oklahoma using core analysis data, open hole, cased hole, tracer, and production data for
material balance.
Conclusion reached:
Each ROS technique offer advantages and limitations. The selection of effective technique
should be based on the formation and wellbore condition. Although some methods has been
improved, further improvement are still needed such as interpretation models, determination of
saturation exponents, and development of inter-well measurement.Resistivity logs tends to give
higher values and coring tends to give lower than average values. ROS zoning and foot-by-foot
comparison between the ROS vertical profiles provide better resolution for ROS comparison.
The comparison offer possibility of studying ROS method discrepancies as a function of depth.
Comments:
The paper gives an objective comment on how each method has its own disadvantages and
includes the uncertainty in measurement and how proper method should be select for different
reservoirconditions.
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Indent: First line: 0 cm
Formatted: Font: Bold
Formatted: Heading 2, Indent: Firstline: 0 cm, Space Before: 0 pt, After: 0 pt, Tab stops: 0.5 cm, List tab
6
Formatted: Right
Formatted: Font: Times New Roman,10 pt
Formatted: Font: Times New Roman,10 pt
A1.3 SPE 30763 - DEPENDENCE OF WATERFLOOD REMAINING OIL SATURATION ON RELATIVE
PERMEABILITY, CAPILLARY PRESSURE, AND RESERVOIR PARAMETERS IN MIXED WET
TURBIDITE SANDS
Authors: G. J. Hirasaki
Contribution Describe the dependencies of residual oil saturation (ROS) on relative
permeability, capillary pressure, and reservoir parameters. The author work with a core sampe of
Turbidite sandstone reservoir. It focus on swept region after waterflooding in water wet and
mixed wet system.
Objective of Paper:
The oil remaining after waterflood operations is sometimes divided into mobile, unswept oil
and immobile, “residual oil saturation” in the swept region. Here the paper will focus only on the
swept region. it will show that the much of the ROS in the swept region may be mobile. The
residual oil saturation, Sor, is defined here as the saturation at which the oil relative permeability
goes to zero. We show that the ROS in the swept region can be very different from S in mixed-
wet systems.
Methodology used:
The author uses finite difference grid reservoir simulation to simulate Buckley-Leverett
displacement process using water-wet and mixed wet core samples.
Conclusion reached:
"A mixed-wet sand may have a low residual oil saturation, Sor. This is a necessary but not
sufficient condition for a low ROS. Other conditions that need to be satisfied for a low ROS are
that (1) the dimensionless time for gravity drainage must be large enough, (2) the sand thickness
should be large compared with the capillary transition zone, and (3) either the mobility ratio be
small or the gravity number be significant compared with unity. In addition, the ROS’s of mixed-
wet systems are sensitive to the shape of the oil relative permeability curve (Corey exponent) and
the mobility ratio. "
Comments:
The paper show the example of using reservoir simulation to calculate ROS using calibrated
core data in mixed we turbidite reservoir which is the part of thesis project workflow.
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Heading 2, Indent: Left: 0cm, First line: 0 cm, Right: 0 cm,Space Before: 0 pt, After: 0 pt
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review1: Critical Literature Review 7
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
A1.4 SPE 19851 - FIELD WIDE VARIATIONS IN RESIDUAL OIL SATURATION IN A SEA SANDSTONE
RESERVOIR
Authors: Davies,G.W.; Gamble,I.J.A.; Heaviside,John
Contribution:
The paper explains the work of extensive coreflood analysis from North Sea sandstone
reservoir to provide reservoir wide description.Various factors are investigated using more than
200 samples. It is also explains ROS distribution in spatial perspective
Objective of Paper:
An extensive set of core waterflood data is analyzed to provide a reservoir-wide description of
residual oil saturation, provide a reservoir-wide description of residual oil saturation, Sor. Such
core tests are influenced by many parameters, including rock structure, wettability, fluid
properties, and experimental procedures. With a data set as large as that used here (more than
procedures. With a data set as large as that used here (more than 200 waterfloods) the effects of
these factors can be separated. It investigated rock structure, permeability, porosity, initial water
saturation, Swi, and wettability. The data indicated that variations in Sor were caused by trends
in Swi and wettability, both of which varied with depth across the transition zone. This implies
that a unique Soi/Sor relationship for this reservoir does not exist. The work presented here was
used to rescale relative permeability data in regions of the field where spatial variation in Swi
exists. The value of the large database for defining trends in reservoir behavior was significant
and enabled more accurate reservoir simulation. Introduction Reservoir performance evaluation
requires accurate description of the displacement processes.
Methodology used:
The paper draws on data produced from many core studies performed over period of time.
The author examines numbers of factors including wettability, flooding method, field procedure,
and laboratory procedures.
Conclusion reached:
Although the lithology of North Sea core is relatively homogeneous, but trends in waterflood
behaviour as a function of height above OWC were observed.Systemic procedures should always
be applied in SCAL analysis so that representative data can be obtained. The particular trend
observed show properties varying with height in the transition zone. Specific differences were
observed in ROS characteristics between samples from oil zone and transition zones.
Comments:
The paper specifically describes ROS characteristics from North Sea sandstone reservoir
generated from various methods and will be a good basis for my upcoming research project.
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Heading 2, Indent: Left: 0cm, First line: 0 cm, Space Before: 0pt, After: 0 pt
8
Formatted: Right
Formatted: Font: Times New Roman,10 pt
Formatted: Font: Times New Roman,10 pt
A1.5 SPE 88628 RESIDUAL OIL SATURATION ANALYSIS OF THE BURGAN FROMATION IN THE
GREATER BURGAN FIELD, KUWAIT.
Authors: Al-Sabea, Salem, Bean, Clarke & Crowe, John
Contribution:
This paper gives an example of integrated residual oil saturation with the case study of
Greater Burgan Field in Kuwait. The paper describe how historical Pulse Neutron Capture log
data could be used to monitor the decreasing residual oil saturation over time and the possibility
of variation in residual saturation in spatial point of view.
Objective of Paper:
This paper is a continuation of some previous study conducted in Greater Burgan reservoir.
Previously, the determinations of residual oil saturation only looks at one type of data at a time
and frequently give different answers. The aim of the current study is to integrate different type
of measurements to produce consistent result.
Methodology used:
Time-lapsed PNC log data from 22 years of field production has been used to monitor flood
front and the remaining oil saturation in the swept zones. This data is then compared to open
hole logs data from newly drilled wells that penetrated the swept zones. Core analysis data from
Dean Stark measurement and core flood test also being used. SMAX imaging method from Core
Laboratories was used to to observe residual oil distribution across the core. During open hole
log analysis, different rock type are identified using rock type flag and probabilistic flag.
Conclusion reached:
Residual oil saturation values might be different for different rock types and area although not
significantly. The different methods of cased hole and open hole logs give a consistent result
with core analysis data.
Comments:
The paper shows how to integrate different type of measurement and relates the result with
time. However this study rely heavily on cased hole logs data which might not be available for
typical North Sea wells which has subsea completion.
Formatted: Font: 11 pt
Formatted: Font: 11 pt
Formatted: Line spacing: single
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review1: Critical Literature Review 9
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
A1.6 SPE 16471 WETTABILITY LITERATURE SURVEY-PART 6: THE EFFECTS OF WETTABILITY ON
WATERFLOODING
Authors: Anderson, W. G.
Contribution:
The paper is a comprehensive literature survey on the effect of wettability to waterflooding.
The author compiled and reviewed various core water flood experiments and observes the impact
of changing wettability to waterflood behaviour. Different wettability state including water wet,
oil wet and mixed wet are discussed and compared to make clear understanding on how different
wetting state could affect oil recovery.
Objective of Paper:
The paper aims to summarise various experimental result on core waterflood study and
discuss the relation of different wetting phase to residual oil saturation, breakthrough time,
cumulative oil recovery, and the period of two phase flow after breakthrough. The paper also
discuss the effect of viscosity ratio on recovery factor and the effect of core handling and
cleaning to the wetting state of the core plugs.
Methodology used:
The author conducted literature survey on various technical publications about core water
flood analysis.
Conclusion reached:
In a strongly water wet sample, most of the oil is produced before breakthrough followed by
small or no oil production afterwards. In water wet system, water act as a continuous phase on
the pore surface making the water sweep become more effective. In the oil wet system, earlier
breakthrough is observed followed by two phase flow for a long period of time. More oil could
be recovered when more PV of water is injected. Oil wet sytem shows lower recovery factor
compared to water wet system. In a mix wet system, water is trapped in the smaller pore which
has water wet behaviour, while oil is trapped in the bigger pore which has oil wet behaviour.
When it comes to water flooding, mix wet system could achieve a very low residual saturation
since most of the oil will be swept out from the bigger pores.
Comments:
The paper provide comprehensive discussion on the effect of different wettability system
could impact the performance of water flood process.
Formatted: Indent: Left: 0.49 cm
Formatted: Normal
10
Formatted: Right
Formatted: Font: Times New Roman,10 pt
Formatted: Font: Times New Roman,10 pt
A1.7 SPWLA 1986-VXXVIIN5A3 SENSITIVITY ANALYSIS OF THE PARAMETERS IN ARCHIE''S
WATER SATURATION EQUATION
Authors: Chen, H. C. & Fang, J. H.
Contribution:
The paper provide a full sensitivity analysis of the Archie water saturation equation, assuming
all six variables in the equatuion to be error prone. The analysis was performed in two models,
(1) Equal uncertainty and (2) unequal uncertainty. The method proposed in the paper enables us
to quantify the error contribution of each parameter. Sensitivity analysis become important when
the measurement of each Archie parameter are not always accurate and highly depends on the
measurement and interpretation technique.
Objective of Paper:
The paper aims to provide simple and direct calculation technique to quantify error in each
Archie parameter by introducing fractional error contribution of each constant. The author tried
to develop a simpler approach of sensitivity analysis for Archie equation compared to the more
complicated Monte Carlo analysis.
Methodology used:
The equation was derived based on standard analysis of errors developed by Bevington (1969)
and then created random variables for each of Archie constants.Total variances of Sw is devided
into six individual variances to create fractional error contribution parameter.
Conclusion reached:
Sensitivity analysis is a study of the sensitivity of a system’s response to various disturbances
in the system. This type of study is essential to well log analysis where algebraic equation such
as Archie call for several parameter whose values may not be accurately known. This method is
found to be as accurate as Monte Carlo simulation. However the time needed for calculation is
much less than Monte Carlo analysis.
Comments:
The paper provide a simple approach to conduct sensitivity analysis for Archie equation
which is essential for the study objective of this project.
Formatted: English (U.K.)
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review1: Critical Literature Review 11
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
A1.8 SPWLA 2004-UUU EVALUATION OF RESIDUAL OIL SATURATION IN THE
BALMORAL FIELD (UKCS)
Authors: Conti, F. & Bona, N.
Contribution:
The paper provide of a case study for residual oil calculation in Balmoral Field in the UK
North Sea using integrated core and log analysis in the swept zone. The author shows that not all
the laboratory analysis result is valid to be taken as a reference for Sor study due to the
associated uncertainty from laboratory procedure and sample condition.
Objective of Paper:
The paper was attempted to investigate the true value of residual oil saturation in Balmoral
Field operated by ENI UK Ltd. The study was triggered by a suspicion that the current Sor value
used in the reservoir simulation might be too high due to the field performance which always
higher than the prediction. It aims to quantify residual oil saturation from logs obtained across
the swept zone of the reservoir,
Methodology used:
The author used open hole logs data which obtained from newly drilled well that exhibit
swept zone. Residual oil saturation was calculated using Archie formula at the swept zone which
exhibit higher resistivity values compared to the water zone. The uncertainty in calculated water
saturation was analyzed using deterministic methods.
Conclusion reached:
True residual oil saturation in Balmoral was find much lower than the one currently used in
the reservoir simulation. The change of Sorw values in simulation improved history matching
which later on provide a better prediction for the reservoir performance.
Comments:
The paper shows a simple yet reliable method of quantifying residual oil saturation from open
hole log data and special core analysis result which is reliable and accurate.
Formatted: Heading 2, Indent: Left: 0.5 cm, Hanging: 1.02 cm, Right: 0cm, Space Before: 0 pt, After: 0 pt
12
Formatted: Right
Formatted: Font: Times New Roman,10 pt
Formatted: Font: Times New Roman,10 pt
A1.9 SPE 39038 OPTIMAL DESIGN AND PLANNING FOR LABORATORY COREFLOODS
Authors: dos Santos, Renato L. A., Bedrikovetsky, P. & Holleben, Carlos R.
Contribution:
The paper provides a method to quantify different effect from laboratory experiments in core
water flood study. The method proposed by the paper could be used for planning a core water
flood test to get a reliable result.
Objective of Paper:
The paper pointed out the conditions that should be fulfilled in order an unsteady state method
of relative permeability measurement becomes valid. The criteriais based on the physical
similarity to waterflooding conducted in the reservoir. This criteria will avoid a laboratory
experiments result from becoming invalid due to numerous effect of different parameters.
Methodology used:
The work of Bedrikovetsky et al for planning the core flood test based on the Barenblatt’s non
equilibrium theory was used a a basis. The proposed method calculates the capillary number,
capillary viscous ratio, and gravity viscous ratio as a screening criterion.
Conclusion reached:
Sample lengths and fluid velocity is the most important factor in order to get a reliable core
flood result. More criteria should be fulfilled when the displacement is using miscible fluid or
EOR fluid such as surfactant or polymer.
Comments:
The method describe in the paper could be used to screen out and select for a reliable
laboratory core flood result from the existing database. This step will be the first step for a sor
determination from core analysis.
Formatted: Space Before: 0 pt
Formatted: Spanish (Venezuela)
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review1: Critical Literature Review 13
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
A1.10 SPE 17686 RESIDUAL OIL SATURATIONS DETERMINED BY CORE ANALYSIS
Authors: Kennaird, T.
Contribution:
The paper discussed the result of laboratory oil displacement experiments using water and gas
which conducted for different purposes such as flood analysis and relative permeability
measurement for various lithologies. The experiments were conducted in different conditions
such as steady state, unsteady state, and centrifuge at both reservoir and ambient temperature.
Objective of Paper:
The paper investigate the value of residual oil saturation which resulted from different type of
measurement and see the impact of different lithology, viscosity ratio, rate, temperature, and
petrophysics feature of each core samples.
Methodology used:
The author conducted water flood experiments to different lithology of core sample in both
room and reservoir temperature using different value of viscosity ratio. The relation of residual
saturation to petrophysical parameter is bein investigated.
Conclusion reached:
Water injection seems to lead to a lower residual oils aturation than gas injection, In assessing
residual oil saturation data, consideration should be given to the test methods. Given the possible
influence of rock water interaction and oil viscosity on oil recovery, a waterflooding test used to
determine residual saturation should preferably reflect what happen in the reservoir.
Consideration should be given to whether or not the reservoir characteristics favour oil
displacement by gravitational forces. Trends exist between residual oil saturation, initial water
satiration and permeability.
Comments:
The paper gives a valuable insight of residual oil determination from various laboratory
methods.
Formatted: Justified
14
Formatted: Right
Formatted: Font: Times New Roman,10 pt
Formatted: Font: Times New Roman,10 pt
A1.11 SPE 3785 RESERVOIR WATERFLOOD RESIDUAL OIL SATURATION FROM LABORATORY
TESTS
Authors: Rathmell, J. J., Braun, P. H. & Perkins, T. K.
Contribution:
The paper presents the results of theoretical and experimental study of laboratory waterflood
and core saturation data which was obtained using water based mud. The paper used previously
published information and its own experimental result.
Objective of Paper:
The paper aims to compare different type of residual saturation measurements by core flood
and dean and stark method on a core sample cutted using water based mud.
Methodology used:
The authors uses fresh core with different type of wettability to conduct laboratory water
flood. Routine core analysis was used as a comparison after the data being adjusted with
bleeding and shrinkage factor.
Conclusion reached:
Laboratory measurement of oil bleeding and shrinkage during the lifting of a core may be
used to adjust the surface oil saturation of the core to reflect the oil saturation before lifting. The
change in oil saturation due to bleeding was found to be about 10% PV for the reservoir cores
which were used in the study. In order to get results representative of the reservoir, laboratory
waterflood must sometimes be carried out using live fluids at reservoir pressure and temperature.
Rocks characteritized as weakly water wet by imbibitions behaviour may have lower residual oil
saturation both at breakthrough and at flood out than rocks that are strongly water wet.
Comments:
The paper provide an understanding of the importance of using live reservoir fluids and
conduct the experiments at reservoir temperature and pressure to match the actual condition of
waterflood in the reservoir.
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review1: Critical Literature Review 15
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
A1.12 SPE 3786 CORE AND LOG DETERMINATION OF RESIDUAL OIL AFTER WATERFLOODING -
TWO CASE HISTORIES.
Authors: Strange, L. K. & Baldwin, W. F.
Contribution:
This is a case study of two fields under waterflood which is assessed for tertiary recovery. The
method of determining residual oil saturation comes from core and log analysis. The paper
investigate the effect of mobile oil and water which lead to flushing during coring operation
which lead the measurement become invalid.
Objective of Paper:
The paper studies two field which are Loudon and Loma Novia field which both under
waterflooding. It used log and core data to assess the potential of two fields to undergo tertiary
recovery
Methodology used:
The paper observe the effect of coring fluid the the measurement of residual oil saturation.
The obtained log data is compared to core measurement to find the degree of flushing and look at
the different result of flushed and non flushed cores.
Conclusion reached:
Conventional rotary cores appear to be superior to cable tool cores from the stand point of
core flushing. While the rubber sleeve core barrel can provide good recovery of unconsolidated
cores, there is evidence that flushing may be more severe than in better consolidated cores.
Electric log techniques proved superior to coring and core analysis to determine oil in place
saturation under the dual mobility conditions.
Comments:
The paper shows the importance of electric log measurement to provide valid saturation
measurements when the core sample are found to be flushed due to the existence of mobile oil
and water during the coring operation.
Formatted: Justified
16
Formatted: Right
Formatted: Font: Times New Roman,10 pt
Formatted: Font: Times New Roman,10 pt
A1.13 SPE 3795 DETERMINATION OF RESIDUAL OIL SATURATION FROM TIME-LAPSE PULSED
NEUTRON CAPTURE LOGS IN A LARGE SANDSTONE RESERVOIR.
Authors: Syed, E. U., Salaita, G. N. & McCaffery, F. G.
Contribution:
The paper shows the utilization of Pulsed Neutron Logs to investigate the relation of residual
oil saturation to the amount of water sweep in the reservoir. The in situ measurement provides a
reliable result since it is free from potential error during the laboratory experiments.
Objective of Paper:
Saturation behind casing is a useful data to monitor the movements of flood front and
unswept zones during waterflood process. The paper describe quantitative determination of
residual oil saturation in water swept zones from numerous wells representing major protions of
the field where water advancement had been dominant.
Methodology used:
The author carried out the work by utilizing PNC log transform developed from the well test
data. The transform was made easier die to the equivalence of the borehole sizes. The paper also
assess the uncertainty in Sor calculation by calculating the total error calculated in water
saturation.
Conclusion reached:
Error analyses suggest that the overall uncertainty in saturations is ranges with porosity
uncertainty being a major factor affecting the analysis results. Errors in initial water saturation
calculations from open hole logs were not included in the uncertainty assessments. The use of
test well PNC log transform provided effective means for time lapse analysis. Formation sigma
traces from early generation tools were converted to equivalent traces for a more accurate tool.
Higher Sor values generally corresponded to deteriorating reservoir rock quality.
Comments:
The paper shows that Sor could be accurately measured using PNC log, and with periodic
survey, a relation of Sor with the function of time could be generated.
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review1: Critical Literature Review 17
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
A1.14 SPE 77545 A UNIFIED THEORY ON RESIDUAL OIL SATURATION AND IRREDUCIBLE WATER
SATURATION.
Authors: Valenti, Nick P., Valenti, R. M. & Koederitz, L. F.
Contribution:
The paper pointed out several classic assumptions used in approximating reservoir recovery in
a small reservoir which is no longer applicable when is used in bigger reservoir. The unified
theory of residual saturation provides a general approach for different type of reservoirs.
Objective of Paper:
The paper define residual oil saturation and irreducible water saturation in the context of
saturation after displacement process is over. It considers capillary force in different type of
laboratory measurement such as drainage/imbibitions capuillary pressure curves, coreflood, and
centrifuge test.
Methodology used:
The author compiles different publication in residual saturation and irreducible oil saturation
measurements and discuss how different condition could lead to different result and might lead
to the wrong decision for tertiary recovery.
Conclusion reached:
Centrifuge tests are recommended over core flood test in terms of obtaining residual oil
saturations and irreducible water saturations. However the maximum centrifuge wpeed must be
correspond with the maximum capillary pressure encountered in the reservoir. The typical
centrifuge and core flood teset result can be reasonably representative for reservoirs with
minimal closure. Using conservative residual oils aturation has yielded an optimistic estimate of
sweep efficiency, therefore forecasting technique such as reservoir simulation model are likely to
underestimate the quantitiy of mobile oil remaining in the reservoir.
Comments:
The current old assumption of residual oil saturation tends to underestimate the true potential
of tertiary oil recovery.
Formatted: English (U.K.)
Formatted: Justified
18
Formatted: Right
Formatted: Font: Times New Roman,10 pt
Formatted: Font: Times New Roman,10 pt
A1.15 SPE 22903-MS DETERMINING EFFECTIVE RESIDUAL OIL SATURATION FOR MIXED
WETTABILITY RESERVOIRS: ENDICOTT FIELD, ALASKA.
Authors: Wood, A. R., Wilcox, T. C., MacDonald, D. G., Flynn, J. J. & Angert, P. F.
Contribution:
The paper explains the significance of mixed wettability to effective water saturation, in
which the value is a function of the amount of PV of water injected.
Objective of Paper:
The paper discuss the residual oilsaturation in Endicott field Alaska which has mix wettability
type rock. The particular wettability is expected to behave differently from the commonly known
water and oil wet reservoir.
Methodology used:
The author used core water flood experiments to observe the behaviour and oil recovery after
breakthrough and also the duration of two phase flow afterwards.
Conclusion reached:
Mix wet reservoir exhibit lower residual saturation com[pared to strongly oil wet and strongly
water wet samples. This is due to the trapping mechanism of water and oil which is trapped in
different size of pores.
Comments:
This paper give a case study of mix wettability reservoir which undergone waterflood.
Previous studies normally only cover
Formatted: Space Before: 0 pt
Formatted: Normal, Indent: Left: 0cm, First line: 0 cm, Right: 0 cm,Space Before: 0 pt, After: 0 pt
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review1: Critical Literature Review 19
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
Formatted: Heading 1, Indent: Left: 0cm, First line: 0 cm, Right: 0 cm,Space Before: 0 pt, After: 0 pt
Formatted
Integration of Residual Hydrocarbon Saturations From Well Logs GGiri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 2 Field Description Figures APPENDIX – 3: Archie Constants CalculationAPPENDIX – 2: Field Description
20
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
Formatted: Tab stops: 17.5 cm,Centered + Not at 18 cm
APPENDIX 2: APPENDIX - 2 FField Description FiguresDescriptions
\The Gryophon Field is located in the South Viking Graben area of the North Sea within Blocks 9/18b and the extreme
southern part of 9/18a, located approximately
Figure A 1 Net Sand Map of Gryphon Area with the Locations of Cored Wells
5597.83 ’ 5600.67 ’ 5603.58 ’ 5606.3
3 ’ 5609.17 ’
5600.67 ’ 5603.58 ’ 5606.33 ’ 5609.17 ’ 5611.88 ’
5597.83 ’ 5600.67 ’ 5603.58 ’ 5606.33
’ 5609.17 ’
5600.67 ’ 5603.58 ’ 5606.33 ’ 5609.17 ’ 5611.88 ’
White Light Core Photograph
Ultra Violet Light Core Photograph
5597.83 ’ 5600.67 ’ 5603.58 ’ 5606.3
3 ’ 5609.17 ’
5600.67 ’ 5603.58 ’ 5606.33 ’ 5609.17 ’ 5611.88 ’
5597.83 ’ 5600.67 ’ 5603.58 ’ 5606.33
’ 5609.17 ’
5600.67 ’ 5603.58 ’ 5606.33 ’ 5609.17 ’ 5611.88 ’
White Light Core Photograph
Ultra Violet Light Core Photograph
5597.83 ’ 5600.67 ’ 5603.58 ’ 5606.33
’ 5609.17 ’
5600.67 ’ 5603.58 ’ 5606.33 ’ 5609.17 ’ 5611.88 ’
5597.83 ’ 5600.67 ’ 5603.58 ’ 5606.33
’ 5609.17 ’
5600.67 ’ 5603.58 ’ 5606.33 ’ 5609.17 ’ 5611.88 ’
White Light Core Photograph
Ultra Violet Light Core Photograph
5597.83 ’ 5600.67 ’ 5603.58 ’ 5606.3
3 ’ 5609.17 ’
5600.67 ’ 5603.58 ’ 5606.33 ’ 5609.17 ’ 5611.88 ’
5597.83 ’ 5600.67 ’ 5603.58 ’ 5606.33
’ 5609.17 ’
5600.67 ’ 5603.58 ’ 5606.33 ’ 5609.17 ’ 5611.88 ’
White Light Core Photograph
Ultra Violet Light Core Photograph
Figure A 2 Core photograph of Well 9/18b-7 Showing Oil Bearing Sandstone
Formatted: Heading 1
Formatted
Field Code Changed
Formatted: Normal
Formatted: Caption, Position:Horizontal: 3.1 cm, Relative to:Column, Vertical: 9.22 cm, Relative to:Paragraph, Horizontal: 0.32 cm, Width:Exactly 13.56 cm, Height: Exactly 0.46cm, Wrap Around
Formatted: Don't keep with next
Formatted: Centered, Keep with next
Formatted: English (U.K.)
Formatted: Centered, Keep with next
Formatted: English (U.K.)
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review2 Field Description Figures1: Critical Literature Review 21
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
Figure A 3 Type Log of Gryphon Area Showing Balder Massive Sandstone
Formatted: Centered, Keep with next
Formatted: English (U.K.)
Integration of Residual Hydrocarbon Saturations From Well Logs GGiri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 2 Field Description Figures APPENDIX – 3: Archie Constants CalculationAPPENDIX – 2: Field Description
22
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
Formatted: Tab stops: 17.5 cm,Centered + Not at 18 cm
-6100
-6000
-5900
-5800
-5700
-5600
-5500
-5400
-5300
-5200
2460 2510 2560 2610 2660 2710 2760
GOC -5541ft ss
OWC -5731ft ss
Gas Gradient
0.03 psi/ft
Oil Gradient 0.37
psi/ft
Water Gradient
0.45 psi/ft
Figure A 4 Composite RFT Data from Gyphon
Figure A 6 Kv/Kh Cross Plot of Balder Massive
Sandstone
Composite RFT Data from Gyphon Wells
Figure A 5 Porosity Permeability Cross Plot of
Balder Massive Sandstone
Formatted: Centered
Formatted: English (U.K.)
Formatted: Centered
Formatted: Caption, Centered, Keepwith next
Formatted: Caption, Centered, Keepwith next
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review2 Field Description Figures1: Critical Literature Review 23
Formatted: Tab stops: 17.75 cm,Centered + Not at 18 cm
Figure A 8 West East Seismic Cross Section of Gryphon Field
Figure A 7 North South Schematic Cross Section of Gryphon Field
Formatted: English (U.K.)
Formatted: English (U.K.)
Formatted: Caption, Centered, Keepwith next
Integration of Residual Hydrocarbon Saturations From Well Logs GGiri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 2 Field Description Figures APPENDIX – 3: Archie Constants CalculationAPPENDIX – 2: Field Description
24
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
Formatted: Tab stops: 17.5 cm,Centered + Not at 18 cm
Figure A 10 North South Schematic Cross Section of Maclure Field
Figure A 9 North South Schematic Cross Section of Harding and Tullich Field
Formatted: Caption, Centered, Keepwith next
Formatted: English (U.K.)
Formatted: Caption, Centered, Keepwith next
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 1: Critical Literature Review2 Field Description Figures1: Critical Literature Review 25
Formatted ...
Table A 11 Reservoir Oil Properties
Gryphon Harding Maclure Tullich
Stock tank oil gravity (API) 21.5 19.3 26.5
Bubble point (psia) @Pb 2504 2504 2503
Rs (scf/stb) @Pb 259 254 330
Bo (rb/stb) @Pb 1.114 1.118 1.114
Oil compressibility (1/psi) (3000 to Pb) 3.92e-06 6.05e-6 7.52e-06
Reservoir oil viscosity 6.7 9.7 5.8
Table A 22 Formation Water Properties
Well
9/18b 7 10 11 12 13 13Z 14 14Y 14Z 16 17 17X 17Y 17Z
Sample
Source RFT RFT RFT RFT RFT RFT RFT RFT RFT RFT RFT RFT RFT RFT
Specific
Gravity 1.049 1.046 1.047 1.045 1.05 1.048 1.04 1.047 1.05 1.046 1.052 1.052 1.052 1.05
Resistivity
@ 60oF
0.142 0.132 0.131 0.14 0.142 0.141 0.135 0.135 0.135 0.138 0.146 0.143 0.132 0.139
pH 6.97 7.03 7.34 7.33 7.33 7.08 8.41 6.95 6.92 7.55 7.13 7.07 8.1 7.68
Formatted: Font: (Default) Arial, 12 pt
Formatted: Font: (Default) Arial, 12 pt
Formatted: Font: (Default) Arial, 12 pt
Formatted: Check spelling andgrammar
Formatted: Normal, Left, Don't keepwith next
Formatted: Font: (Default) Arial
Formatted: Font: (Default) Arial
Formatted: Font: (Default) Arial, NotBold
Formatted: Font: (Default) Arial
Formatted: Font: (Default) Arial, NotBold
Formatted: Font: (Default) Arial
Formatted: Font: (Default) Arial, NotBold
Formatted: Font: (Default) Arial
Formatted: Font: (Default) Arial, NotBold
Formatted: Font: (Default) Arial
Formatted: Font: (Default) Arial, NotBold
Formatted: Font: (Default) Arial
Formatted: Font: (Default) Arial, NotBold
Formatted: Centered
Formatted: Font: (Default) Arial, 12 pt
Formatted: Font: (Default) Arial, 12 pt
Formatted: Font: (Default) Arial, 12 pt
Formatted: Centered, Keep with next
Formatted: Position: Horizontal: Left,Relative to: Margin, Vertical: 8.45 cm,Relative to: Page
Formatted Table
Formatted: Font: Bold
Formatted: Font: Not Bold
Formatted ...
Formatted
Formatted: Font: Not Bold
Formatted ...
Formatted
Formatted: Font: Not Bold
Formatted ...
Formatted
Formatted: Font: Not Bold
Formatted ...
Formatted: Centered, Keep with next
Integration of Residual Hydrocarbon Saturations From Well Logs GGiri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 3: Log AnalysisAPPENDIX – 3: Archie Constants CalculationAPPENDIX – 2: Field Description
26
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
Formatted: Tab stops: 17.5 cm,Centered + Not at 18 cm
Saturation Exponent Histogram (n)
0
1
2
3
4
5
6
11.
31.
61.
92.
22.
52.
83.
13.
43.
7 44.
34.
64.
9
Saturation Exponent (n)
Fre
qu
en
cy
0
10
20
30
40
50
60
70
80
90
100
Pe
rce
nta
ge
n
Cummulative frequency
Cementation Factor Histogram (m)
0
1
2
3
4
5
6
7
8
1.51.
531.
561.
591.
621.
651.
681.
721.
751.
781.
811.
841.
87 1.9
1.93
1.96
1.99
Cementation Factor (m)
Fre
qu
en
cy
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
Pe
rce
nta
ge
m
Cummulative frequency
APPENDIX - 3 Archie Constants Log AnalysisCalculation
Figure A 11 Histogram of Core Derived Cementation Factor
Figure A 12 Histogram of Core Derived Saturation Exponent
Formatted: Heading 1
Formatted: Font: Arial
Formatted: Font: Arial
Formatted: Caption, Centered, Keepwith next
Formatted: English (U.K.)
Formatted: Caption, Centered, Keepwith next
Formatted: English (U.K.)
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 3: Log AnalysisAPPENDIX – 3: Archie Constants Calculation 27
Formatted: Tab stops: 17.5 cm,Centered + Not at 18 cm
Histogram of COMPOSITE.RWAWell: 19 Wells
Range: All of WellFilter: REFERENCE.TVDSS>5731&COMPOSITE.PHIE>0.1
0.0
0.2
0.4
0.6
0.8
1.0
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.0
1
0.1 1
Percentiles:
5% 0.0324150% 0.0583395% 0.10907
Statistics:
Possible values 7359Missing values 0Minimum value 0.00913Maximum value 15.31219Range 15.30306
Mean 0.07260Geometric Mean 0.05809Harmonic Mean 0.05367
Variance 0.11079Standard Deviation 0.33285Skewness 40.53374Kurtosis 1733.51089Median 0.05833Mode 0.06166
7359
7344
3 12
Figure A 13 Histogram of Log Derived Apparent Water Resistivity (Rwa) Formatted: Caption, Centered, Keepwith next
Integration of Residual Hydrocarbon Saturations From Well Logs GGiri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 3: Log AnalysisAPPENDIX – 3: Archie Constants CalculationAPPENDIX – 2: Field Description
28
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
Formatted: Tab stops: 17.5 cm,Centered + Not at 18 cm
Log Analysis
APPENDIX 3:
Figure A 14 Harding Well 9/23b-A29 Open Hole Log
Formatted: Centered
Formatted: Centered, Keep with next
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 3: Log AnalysisAPPENDIX – 3: Archie Constants Calculation 29
Formatted: Tab stops: 17.5 cm,Centered + Not at 18 cm
Figure A 1515154 HardingGryphon Well 9/1823b-30AA29 Open Hole Log
Formatted: Centered, Keep with next
Integration of Residual Hydrocarbon Saturations From Well Logs GGiri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 3: Log AnalysisAPPENDIX – 3: Archie Constants CalculationAPPENDIX – 2: Field Description
30
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
Formatted: Tab stops: 17.5 cm,Centered + Not at 18 cm
Histogram of COMPOSITE.RWAWell: 19 Wells
Range: All of WellFilter: REFERENCE.TVDSS>5731&COMPOSITE.PHIE>0.1
0.0
0.2
0.4
0.6
0.8
1.0
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.0
1
0.1 1
Percentiles:
5% 0.0324150% 0.0583395% 0.10907
Statistics:
Possible values 7359Missing values 0Minimum value 0.00913Maximum value 15.31219Range 15.30306
Mean 0.07260Geometric Mean 0.05809Harmonic Mean 0.05367
Variance 0.11079Standard Deviation 0.33285Skewness 40.53374Kurtosis 1733.51089Median 0.05833Mode 0.06166
7359
7344
3 12
Formatted: English (U.S.), Checkspelling and grammar
Formatted: Heading 1
Formatted: Section start: New page
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 3: Archie Constants 4: Core Analysis DataCalculation 31
Formatted: Tab stops: 17.5 cm,Centered + Not at 18 cm
Harding SCAL Distribution
FRF @ NOB Pressure, 29
FRI @ NOB Pressure, 14
Water-Oil PC, 6
Mercury Injection, 6
Cation Exchange
Capacity, 7
Gas-Oil Rel Perm, 12
Water-Oil Rel Perm, 13
Waterflood Susceptibility
Analysis, 6
Por as Function of
Overburden, 7
XRD Analysis, 7
Por-perm @ Overburden
Pressure, 10
Air Brine PC, 7
PV Compressibility, 4
FRF @ NOB Pressure
FRI @ NOB Pressure
Water-Oil PC
Mercury Injection
Air Brine PC
Cation Exchange Capacity
Gas-Oil Rel Perm
Water-Oil Rel Perm
PV Compressibility
Waterflood Susceptibility Analysis
Por as Function of Overburden
XRD Analysis
Por-perm @ Overburden Pressure
SCAL Wells
Gryphon, 7
Maclure, 2
Tullich, 1
Harding, 4
Gryphon
Maclure
Tullich
Harding
Gryphon SCAL Distribution
Oil/Water Rel Perm, 55
Gas/Oil Rel Perm, 29
Wettability, 71
Electrical properties, 87
Waterflood Susceptibility,
33
Irreducible Sw, 18
Uniaxial & Hydrostatic
Compressibility, 5
Por-perm at Overburden,
29
Capillary pressure, 35Oil/Water Rel Perm
Gas/Oil Rel Perm
Wettability
Electrical properties
Waterflood Susceptibility
Irreducible Sw
Uniaxial & Hydrostatic Compressibility
Por-perm at Overburden
Capillary pressure
APPENDIX 4: APPENDIX - 4 Relative Permeability Data RefinementCore
Analysis
Figure A 1616187 Pie Chart of the Number of Plugs for Different SCAL Analysis in Harding
Field
Figure A 1818168 Pie Chart of the Number of SCAL Wells
Figure A 1717176 Pie Chart of the Number of Plugs for Different SCAL Analysis in Gryphon
Field
Formatted: Heading 1, Don't keepwith next
Formatted
Field Code Changed
Formatted: English (U.S.), Checkspelling and grammar
Formatted: Caption, Centered, Keepwith next
Formatted: Centered, Keep with next
Integration of Residual Hydrocarbon Saturations From Well Logs GGiri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 4: Core Analysis DataAPPENDIX – 45: Relative Permeability Data Refinements
32
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
Maclure SCAL Distribution
Sw Irreducible, 17
AMOTT Wettability, 6
Oil/Water Rel Perm, 13FRF @ Overburden
Pressure, 9
Capillary Pressure, 9
FRI @ Overburden
Pressure, 4
PV Compressibility, 3
Kw @ Overburden
Pressure, 5
Porosity @ Overburden
Pressure, 5 Sw Irreducible
AMOTT Wettability
Oil/Water Rel Perm
FRF @ Overburden Pressure
Capillary Pressure
FRI @ Overburden Pressure
PV Compressibility
Kw @ Overburden Pressure
Porosity @ Overburden Pressure
Figure A 1919189 Pie Chart of the Number of Plugs for Different SCAL Analysis in Maclure
Field
Tullich SCAL Distribution
FRF @ Ambient Pressure,
4
FRI @ Overburden
Pressure, 4
PV Compressibility, 4
Air-Brine Capillary
Pressure, 4
Oil-Water Rel Perm, 8
Core Saturation, 8
Mercury Injection, 4
X-ray Diffraction, 4
Cation Exchange
Capacity, 4FRF @ Ambient Pressure
FRI @ Overburden Pressure
PV Compressibility
Air-Brine Capillary Pressure
Oil-Water Rel Perm
Core Saturation
Mercury Injection
X-ray Diffraction
Cation Exchange Capacity
Figure A 20201209 Pie Chart of the Number of Plugs for Different SCAL Analysis in Tullich
Field
Formatted: Caption, Centered, Keepwith next
Formatted: Caption, Centered, Keepwith next
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 3: Archie Constants 4: Core Analysis DataCalculation 33
Formatted: Tab stops: 17.5 cm,Centered + Not at 18 cm
Dean Stark Histogram
0
2
4
6
8
10
12
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
Sor (%)
Fre
qu
en
cy
0.00%
20.00%
40.00%
60.00%
80.00%
100.00%
120.00%
Frequency
Cumulative %
Figure A 2121210 Histogram of Oil Saturation From Dean Stark Analysis
Formatted: Caption, Centered, Keepwith next
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 5: Relative Permeability Data Refinements APPENDIX – 45: Relative Permeability Data
Refinements 34
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00K
r
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
APPENDIX 5: Relative Permeability Data Refinement
Fig. A 1 Rel Perm Data from
Sample 17-87VA
Fig. A 2 Rel Perm Data from
Sample 17-94VC
Fig. A 3 Rel Perm Data from
Sample 17-120VB
Fig. A 4 Rel Perm Data from
Sample 17-134VA
Fig. A 5 Rel Perm Data from
Sample 14-A3
Fig. A 10 Rel Perm Data from
Sample 12-229VA
Fig. A 7 Rel Perm Data from
Sample 14-D2
Fig. A 8 Rel Perm Data from
Sample 13-Test
Fig. A 9 Rel Perm Data from
Sample 12-Test
Fig. A 6 Rel Perm Data from
Sample 14-B3
Formatted: Left: 3.05 cm, Right: 0.95 cm, Top: 1.52 cm, Bottom: 1.52cm, Width: 29.7 cm, Height: 21 cm
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 5: Relative Permeability Data Refinements APPENDIX – 5: Sector Model
35
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
Fig. A 10 Rel Perm Data from
Sample 12-206V
Fig. A 10 Rel Perm Data from
Sample 12-82V
Fig. A 10 Rel Perm Data from
Sample 11-10V
Fig. A 10 Rel Perm Data from
Sample 11-49V
Fig. A 10 Rel Perm Data from
Sample 11-105V
Fig. A 10 Rel Perm Data from
Sample 11-178V
Fig. A 10 Rel Perm Data from
Sample 11-44V
Fig. A 10 Rel Perm Data from
Sample 11-109V
Fig. A 10 Rel Perm Data from
Sample 11-176V
Fig. A 10 Rel Perm Data from
Sample 11-15V
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 5: Relative Permeability Data Refinements APPENDIX – 45: Relative Permeability Data
Refinements 36
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
Fig. A 10 Rel Perm Data from
Sample 11-16V Fig. A 10 Rel Perm Data from
Sample 11-89VA
Fig. A 10 Rel Perm Data from
Sample 11-13V
Fig. A 10 Rel Perm Data from
Sample 11-15V2
Fig. A 10 Rel Perm Data from
Sample 11-16V2
Fig. A 10 Rel Perm Data from
Sample 11-11
Fig. A 10 Rel Perm Data from
Sample 11-12
Fig. A 10 Rel Perm Data from
Sample 11-16
Fig. A 10 Rel Perm Data from
Sample 11-17
Fig. A 10 Rel Perm Data from
Sample 11-50
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 5: Relative Permeability Data Refinements APPENDIX – 5: Sector Model
37
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.0
0.2
0.4
0.6
0.8
1.0
0.0 0.2 0.4 0.6 0.8 1.0
Kr
Sw
Curve Refinement
Krw
Kro
Krw, ref.
Kro, ref.
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
Fig. A 10 Rel Perm Data from
Sample 11-105
Fig. A 10 Rel Perm Data from
Sample 11-51
Fig. A 10 Rel Perm Data from
Sample 11-106
Fig. A 10 Rel Perm Data from
Sample 11-108
Fig. A 10 Rel Perm Data from
Sample 11-109
Fig. A 10 Rel Perm Data from
Sample 11-143
Fig. A 10 Rel Perm Data from
Sample 11-144
Fig. A 10 Rel Perm Data from
Sample 11-167
Fig. A 10 Rel Perm Data from
Sample 11-168
Fig. A 10 Rel Perm Data from
Sample 10-13B
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 5: Relative Permeability Data Refinements APPENDIX – 45: Relative Permeability Data
Refinements 38
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
Krw, ref.
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
Fig. A 10 Rel Perm Data from
Sample 7-9D
Fig. A 10 Rel Perm Data from
Sample 7-8D
Fig. A 10 Rel Perm Data from
Sample 7-7D
Fig. A 10 Rel Perm Data from
Sample 7-6D
Fig. A 10 Rel Perm Data from
Sample 7-5D
Fig. A 10 Rel Perm Data from
Sample 7-4D
Fig. A 10 Rel Perm Data from
Sample 7-3D
Fig. A 10 Rel Perm Data from
Sample 7-2D
Fig. A 10 Rel Perm Data from
Sample 7-1D
Fig. A 10 Rel Perm Data from
Sample 10-14A
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Formatted: Caption
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 5: Relative Permeability Data Refinements APPENDIX – 5: Sector Model
39
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.20 0.40 0.60 0.80 1.00
Kr
Sw
Curve Refinement
Krw
Kro
`
Fig. A 10 Rel Perm Data from
Sample 7-10D
Fig. A 10 Rel Perm Data from
Sample 12-205VA Formatted: Caption
Formatted: Caption
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 5: Relative Permeability Data Refinements
APPENDIX – 5: Sector Model 41
APPENDIX - 5 Core Analysis
Routine core analysis including core gamma measurement, core slabbing, core sampling core cleaning and drying, porosity
and permeability measurement, and saturation determination by both retort distillation method and Dean and Stark Analysis.
The plugs are cut about 2-3 inches long and 1.5 inch in diameter in SCAL analysis before loaded into hydrostatic core holder
where overburden pressure were applied. Subsequently each plug was flushed with 200 cP bland mineral oil at 200C and
followed by flushing with 20 cP mineral oil to determine irreducible water saturation and permeability to oil (Kro at Swc).
Formatted: Font: Arial
Formatted: Heading 1
Formatted
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 6: Buckley Leverett Calculation 42
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
APPENDIX 6: APPENDIX - 6 Buckley Leverett Calculations
Figure A 222221 Workflow of Buckley Leverett Analysis to Calculate Oil Saturation as A Function of PV Water
Sweep
Formatted: Font: Arial
Formatted: Heading 1
Formatted: Caption, Centered, Keepwith next
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridita Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 7: Impact of SORW to Recovery Prediction and History Match 43
APPENDIX 7: APPENDIX - 7 Impact of SORW to Recovery Prediction and History Match
Figure A 242422 Comparison of Field Oil Production Rate from Different Sor Cases with Actual Production Rate
Figure A 232323 Comparison of Field Water Production Rate from Different Sor Cases with Actual Production Rate
Formatted: Font: Arial
Formatted: Heading 1
Formatted
Formatted: Caption, Centered, Keepwith next
Formatted: Caption, Centered, Keepwith next
Integration of Residual Hydrocarbon Saturations From Well Logs Giri Aridiita ta Identified Swept Zones With Relative Permeability and Core Saturation Data MSc in Petroleum Engineering 2009/2010
APPENDIX – 7: Impact of SORW to Recovery Prediction and History Match 44
Formatted: Tab stops: 17.75 cm,Right + Not at 19.05 cm
Figure A 252525 Comparison of Field Gas Production Rate from Different Sor Cases with Actual Production Rate
Figure A 262624 Comparison of Field Water Cut Production Rate from Different Sor Cases with Actual Production
Rate
Formatted: Caption, Centered, Keepwith next
Formatted: Caption, Centered, Keepwith next