EvaluationEvaluation

Geological Engineering BasicsGeological Engineering Basics

GEOL 4233 ClassGEOL 4233 Class

Dan BoydDan BoydOklahoma Geological SurveyOklahoma Geological Survey

Fall 2011 SemesterFall 2011 Semester

Geological Engineering Overview

• Reservoir Issues• Porosity• Permeability• Fluid Saturation

• Fluid / Pressure Terminology & Concepts• Fluid (Water, Oil Gas)• Pressure (Saturation, Mobility, Compressibility)

• Drive Mechanisms• Oil• Gas• Multiphase Flow Issues (Coning)

• Reservoir Management• General Principles• Production Curves• Improved Recovery

General Reservoir Issues

•Porosity

•Permeability

•Fluid Saturations

Porosity• Storage Capacity

• Nominal Pay Cutoffs• Oil: 10%• Gas: 8%

• Porosity Types• Intergranular (clastics)• Intercrystaline (carbonates)• Fracture• Dissolution (moldic, vuggy, cavernous)

• Logs• Density• Neutron• Sonic

Booch Core Porosity vs. Depth

Schematic Porosity vs. Depth Plot

5,000’ 20,000’15,000’10,000’

(Hard Rock Country)

Permeability• Producibility

• Kv – Kh (vertical vs. horizontal)• Conventional Reservoirs• Fractured Reservoirs• Unconventional Reservoirs

• Relative Permeability

• Enhanced Permeability• Acid Treatment• Fracture Stimulation

• Logs• Spontaneous Potential (SP)• Resistivity Suite

Booch Core Porosity vs. Permeability(Maximum Values)

Core Porosity vs. Permeability Plot

Fluid Saturation• Water

• Wetting (dewatering)• Connate• Irreducible (Swirr)

• Oil • Water displacement (Soi)• Fractured Reservoirs• Unconventional Reservoirs

• Gas• Molecular Size (mobility) • Water/Oil displacement (Sgi)

Grain Size (permeability)

Water Saturation

Shale (Magnified)

Initial (complete pore volume) – Irreducible (rims only)

Schematic Reservoir Grain Size vs. Water Saturation

Reservoir SandstoneReservoir Sandstone

Good Porosity = Lots of Space for PetroleumGood Porosity = Lots of Space for Petroleum

Pores(blue)

Conventional vs. Non-Conventional Gas Accumulations

Water Saturation vs. Porosity(Taken from Booch Brooken Gas Field Study)

0

5

10

15

20

25

30

40 30 20 15 10

Swi

Por

osity

1 Inch1 Inch

Shale(Organic-Rich)

Unconventional (Low-Perm)

Pressures / Fluids

Fluid Terminology

Water:Connate

Movable vs. Irreducible

Grain Size (permeability)

Water Saturation

Shale (Magnified)

Initial (complete pore volume) – Irreducible (rims only)

Schematic Reservoir Grain Size vs. Water Saturation

Fluid Terminology

Water:Connate

Movable vs. Irreducible

Salinity (ppm): Chlorides vs. T.D.S.

Fresh – Brackish – Normal Marine - Hypersaline

Secondary Recovery (Waterflood)

Compressibility (10x rule)

Water Support Likely

Water Support Unlikely

Fluid Terminology

Oil:Gravity (API)

Viscosity (cp)

GOR (gas to oil ratio)

Saturated vs. Undersaturated (gas cap – secondary gas cap)

Fluid Terminology

Oil:Gravity (API)

Viscosity (cp)

GOR (gas to oil ratio)

Saturated vs. Undersaturated (gas cap – secondary gas cap)

Contrast with Condensate

Live vs. Dead

Sweet vs. Sour

Fluid Terminology

Gas:

Heating Value

Condensate Yield

Condensate vs. Oil

Wet vs. Dry

Sweet vs. Sour

Other Components (CO2, N2)

Pressure Terminology

‘Normal’ Pressure (hydrostatic)

Under-pressure (fluid leak-off or storage volume increase)

Over-pressure (incomplete de-watering)

Measurements:Reservoir Pressure (BHP, calculated vs. measured)

Flowing Tubing Pressure (FTP, at surface)

Casing Pressure (between casing and tubing)

c

Saturation Pressures

Oil : Bubble Point

Gas : Dew Point (retrograde – occurs in reservoir)

Fluid Mobility / Compressibility

Molecular Size Mobility Compressibility

• Gas - Small High Very High

• Oil - Large Medium Moderate (~GOR)

• Water - Medium Low Low (10x Rule)

Drive Mechanisms

Oil ReservoirDrive Mechanisms

• Solution Gas Drive (dissolved gas) (also called depletion)

• Gas Expansion Drive (gas cap)

• Water Drive

• Combination Drive

• Gravity Drainage

Unconformity Trap

Schematic Gravity Drainage

Shallow (Low Pressure)

Gas Reservoirs

Gas Reservoir Drive Mechanism

Gas

Gas / WaterContact

Dominantly Depletion

Coalbed Methane Production

Coalbed Methane Well (Oklahoma)

GasGas

OilOilWaterWater

American Petroleum Institute, 1986American Petroleum Institute, 1986

Multi-Phase Flow Issues

“ D 6 “ HORIZONTAL WELLBORE TRAJECTORIES

LOWER D6 ( S 36 )STRUCTURE

NET SAND

S.L.-7150

B-94

B-181

B-46

B-98

B-92

0 1000 M.200 400 600 800

B-54

B-99

0

10

2020

3040

20

10

0

4030

20

B-56 0

-7200

40

30

B-69

B - 184 LATERAL

N

B - 185 L

ATERAL

10

50

50

B-176

-7100

-7150S.L.

BADAK - 185 HORIZONTALSCHEMATIC WELLBORE

STRATIGRAPHY( VERTICAL EXAGGERATION = 20X )

-7090’

PILOT HOLE 7800 8000 8400 8600 8800 9000 9200

MEASURED DEPTHTVD SS

-7100’

-7110’

-7120’

-7130’

-7140’

-7150’

INITIAL TARGET DEPTH

B-184 PILOTGOC

~ OIL RIM UPPER LIMIT IN PILOT

BEGIN O/W TRANSITION ZONE IN PILOT

50 % Sw IN PILOT

8200

S 36

S 33

(Elan Plus Interpretation)

Badak-185 Horizontal Lateral

Pressure Gradients

Pressure Gradients

Reservoir Management

Preservation of Reservoir Energy (pressure)

Water into the bottom

Gas into the top

Long term gain for short term pain (production restraint)

General Principles

Production

• Primary

• Secondary (Waterflood)

• Tertiary (Enhanced)

Strong City Field Gas Production

1988 1991 1994 1997 2000 2003 2006 20092,828

202,828

402,828

602,828

802,828

1,002,828

COSTILOW - WILBURTON

Time

Pro

duct

ion

Rat

es

Oil Production (bbl)Gas Production (mcf)

Oil Production (bbl)Gas Production (mcf)

Vertical Arbuckle Gas Well

Cum: 44.5 BCF

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008137

1,137

2,137

3,137

4,137

ROSSON VERNON - HOLLOW NORTHWEST

Time

Pro

duct

ion

Rat

es

Oil Production (bbl)

Gas Production (mcf)

Oil Production (bbl)Gas Production (mcf)

Vertical Coalbed Methane Well (Cherokee Platform)

1983 1986 1989 1992 1995 1998 2001 2004 2007 2010253

5,253

10,253

15,253

20,253

25,253

ARMY CORPS OF ENG - BROOKEN

Time

Pro

duct

ion

Rat

es

Oil Production (bbl)

Gas Production (mcf)

Oil Production (bbl)Gas Production (mcf)

Vertical Hartshorne Coalbed Methane Well

2005 2006 2007 200825

5,025

10,025

15,025

20,025

DENNY - HASKELL COUNTY CBM GAS AREA

Time

Pro

duct

ion

Rat

es

Oil Production (bbl)

Gas Production (mcf)

Oil Production (bbl)Gas Production (mcf)

Horizontal Hartshorne Coalbed Methane Well

1974 1978 1982 1986 1990 1994 1998 2002 2006 20101

20,001

40,001

60,001

80,001

HAYNIE - AYLESWORTH DISTRICT SOUTHEAST

Time

Pro

duct

ion

Rat

es

Oil Production (bbl)

Gas Production (mcf)

Oil Production (bbl)Gas Production (mcf)

Vertical Woodford Gas Well

2006 2007 200823,062

43,062

63,062

83,062

PASQUALI - CHILES DOME

Time

Pro

duct

ion

Rat

es

Oil Production (bbl)

Gas Production (mcf)

Oil Production (bbl)Gas Production (mcf)

Horizontal Woodford Gas Well

Horizontal Woodford Gas Well

2007 2008197,827

297,827

397,827

SHERMAN ELLIS - PINE HOLLOW SOUTH

Time

Pro

duct

ion

Rat

es

Oil Production (bbl)

Gas Production (mcf)

Oil Production (bbl)Gas Production (mcf)

Remedial work ?

1982 1985 1988 1991 1994 1997 2000 2003 2006 2009104

2,104

4,104

6,104

8,104

VANN C - PERRY

Time

Pro

duct

ion

Rat

es

Oil Production (bbl)

Gas Production (mcf)

Oil Production (bbl)Gas Production (mcf)

Misener Oil Well

Cum: 670 MBO + 207 MMCFCurrent Rate: 24 BOPD

Approximately 240 MMCF Vented

Primary Recovery

Improving Recovery

Secondary (Waterflood)

Enhanced (Tertiary)

Secondary Secondary RecoveryRecovery

WaterWater

GasGas

SteamSteam

ChemicalChemical

FireFire

Pumped into the Pumped into the reservoir to force reservoir to force additional petroleum additional petroleum out of the pores in the out of the pores in the reservoir rockreservoir rock

InjectionInjectionWellsWells

Producing WellsProducing Wells

Of 60% Remaining Of 60% Remaining in Reservoirin Reservoir

Tecumseh NW Field Example of Ideal Primary – Secondary Production Curve

Shawnee Lake SE Field

Secondary 2/3rds of total production

Enhanced Recovery

Postle Field Oil Production

Next:

Volumetrics

(Bring a calculator and straight edge to class)