New Application of Sonic Scanner*

in Gas Reservoir Evaluation

Ronarong ParamatikulPetrophysics Domain EngineerData & Consulting Services

Schlumberger

� Challenges in Gas Evaluation

� Idea of using Sonic Scanner for Gas Evaluation

� Processing & Interpretation Workflow

Agenda

2

� Processing & Interpretation Workflow

� Application & Benefit of the New Technique

� Conclusion

GR Resistivity Neutron-Density

Gas Field

Oil Field

Challenges in gas evaluation

3

Gas Sand

Gas show

during drilling

Source: World Energy Atlas 2002

� Sonic Scanner

� Combination of monopole and dipole transmitters

� 13 arrays of receivers

Sonic measurement is a good gas indicator

4

� Good quality of waveforms for future applications

MU ML MFXD YD

13 x Receivers

� Sonic measurement is mainly used for Geophysics & Geomechanics, but not Petrophysics

� Sonic measurement is very good gas indicator

� Transform compressional & shear slowness into modulus

How to use sonic for gas evaluation?

5

� Transform compressional & shear slowness into modulus

� Use modulus as saturation input to compute gas saturation

Qualitative Quantitative

Gas sand? How much gas?

Gas detection from Sonic

6

Gas effect on sonic data

Conve

ntional

Sonic Scanner into ELAN Workflow

Data QC

Environmental Correction

Resistivity ELAN

Sonic Scanner

Processing

Data QC

Environmental Correction

Resistivity ELAN

Sonic Scanner

Processing

New

work

flow

7

Bulk & Shear

Modulus Calculation

Sonic Endpoints

Calibration

Sonic ELAN

Result Review

Bulk & Shear

Modulus Calculation

Sonic Endpoints

Calibration

Sonic ELAN

Result Review

QC & Env Correct Resistivity ELAN Sonic Scanner Modulus Endpoints Sonic ELAN Result Review

Data QC & Environmental Correction

Logging Parameters & Field CalibrationEnvironmental Correction� Logging parameters

� Field calibrations

� Environmental correction

8

Good Quality Log For Interpretation

Resistivity ELAN Sonic Scanner Modulus Endpoints Sonic ELAN Result ReviewQC & Env Correct

Resistivity ELAN Interpretation

� ELAN is Petrophysical

Interpretation module

� Cross plot analysis to determine

endpoints

Equations

Volume

Result

GR ResistivityNeutron

Density Resistivity ELAN

9

� Use resistivity as equation for

water saturation

Shale endpointD

ensi

ty

Neutron porosity

QC & Env Correct Sonic Scanner Modulus Endpoints Sonic ELAN Result ReviewResistivity ELAN

Use for Sonic Calibration

Sonic Scanner Processing

� Sonic waveform preprocessing

� Compressional & Shear

Slowness by BestDT module

Compressional Shear

10

Unpack & QC Sonic Scanner waveforms

QC & Env Correct Resistivity ELAN Modulus Endpoints Sonic ELAN Result ReviewSonic Scanner

Input for the next step

Bulk Modulus & Shear Modulus Calculation

� Modulus from Sonic wave

� Slowness to Modulus conversion

� Effect of Bulk modulus to gas

Gas effect on bulk modulus

11QC & Env Correct Resistivity ELAN Sonic Scanner Endpoints Sonic ELAN Result ReviewModulus

M = Vp2 x ρ

Bulk Modulus = K = M – (4 G /3)

M = Compressional Modulus

G = Shear Modulus

G = Vs2 x ρ

G =(13474.45 x ρb) / (∆tsh)2

M =(13474.45 x ρb ) / (∆tco)2

K = M – (4G / 3)

Conversion to Slowness

Gas effect on bulk modulus

It can be use for Saturation input

New input curves computed

Sonic Endpoints Calibration

12QC & Env Correct Resistivity ELAN Sonic Scanner Modulus Sonic ELAN Result ReviewEndpoints

Volume from Resistivity ELAN Calibration Calibrated data

Sonic ELAN Interpretation

� Sonic ELAN Model

� Use sonic modulus to be

saturation input

GR ModulusNeutron

Density Sonic ELAN

QC & Env Correct Resistivity ELAN Sonic Scanner Modulus Endpoints Result ReviewSonic ELAN

Results and Finding

GR ResistivityNeutron

Density ModulusResistivity

ELAN

Sonic

ELAN� Over calibrated interval

Sonic – Resistivity very similar result

� Outside calibrated interval

Sonic – Resistivity very similar result

� What is the different?

Sonic see something where resistivity

14

Sonic see something where resistivity

cannot see

� Sonic detects gas in the formation

where Resistivity does not

QC & Env Correct Resistivity ELAN Sonic Scanner Modulus Endpoints Sonic ELAN Result Review

Sg > 15%Sg < 3%More gas identified

Applications

1. Sonic interpretation is independent of formation water salinity

2. Sonic sees gas where Resistivity could not e.g. thinly laminated sands

15

3. Cased hole gas saturation evaluation

4. Offset wells where no Resistivity data recorded

Example: Well-A to Well-B

All parameters from Well-A

to Well-B

Gas observed in shaly zone

16

Resistivity ELAN Sonic ELAN

Example: Thin beds sand with gas

17T-combo with RT Scanner Resistivity ELAN Sonic ELAN OBMI Image

Example: Thin beds sand with gas

Gas seen from

Sonic

18T-combo with RT Scanner Resistivity ELAN Sonic ELAN OBMI Image

Example: Thin beds sand with gas

Gas seen from

Sonic

19T-combo with RT Scanner Resistivity ELAN Sonic ELAN OBMI Image

Example: Thin beds sand with gas

Gas seen from

Sonic

20T-combo with RT Scanner Resistivity ELAN Sonic ELAN OBMI Image

Benefit of using the technique

1. Reduce uncertainty in formation evaluation

2. Gas evaluation in low resistivity pay (e.g. Laminated sand)

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3. New option for gas analysis behind casing

Formation Evaluation

Resistivity RST C/ONMR diffusion

editing

22

Dielectric Downhole

Fluid

Analyzer

Neutron

Time lapseGas detection

from SonicGas Saturation

from Sonic

New option for Gas evaluation

THANK YOUTHANK YOU

Q & A

Backup Slides

25

LWD Sonic vs WL Sonic in Fast Formation

� Good comparable

Compressional – Shear

slowness between

SonicVISION vs DSI

SonicVISION compared to DSI

Dipole Transmitters

DSI Sonic Scanner