Transcript Document

Evaluation
Geological Engineering Basics
GEOL 4233 Class
April 21, 2008
Dan Boyd
Oklahoma Geological Survey
Norman, Oklahoma
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
(Hard Rock Country)
5,000’
10,000’
15,000’
20,000’
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)
Schematic Reservoir Grain Size vs. Water Saturation
Grain Size (permeability)
Shale (Magnified)
Water Saturation
Initial (complete pore volume) – Irreducible (rims only)
Reservoir Sandstone
Good 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)
30
Porosity
25
20
15
10
5
0
40
30
20
Swi
15
10
Unconventional (Low-Perm)
Shale
(Organic-Rich)
1 Inch
Pressures / Fluids
Fluid Terminology
Water:
Connate
Movable vs. Irreducible
Schematic Reservoir Grain Size vs. Water Saturation
Grain Size (permeability)
Shale (Magnified)
Water Saturation
Initial (complete pore volume) – Irreducible (rims only)
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)
Simple Fault Trap
(Narrow Horst)
Extensional
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)
Over-pressure (incomplete de-watering)
Measurements:
Reservoir Pressure (BHP, calculated vs. measured)
Flowing Tubing Pressure (FTP, at surface)
Casing Pressure (between casing and tubing)
Saturation Pressures
Oil :
Gas :
Bubble Point
Dew Point (retrograde – occurs in reservoir)
Fluid Mobility / Compressibility
•
Gas
•
Oil
•
Water
Drive Mechanisms
Oil Reservoir
Drive Mechanisms
• Solution Gas Drive (dissolved gas) (also called depletion)
• Gas Expansion Drive (gas cap)
• Water Drive
• Combination Drive
• Gravity Drainage
Unconformity Trap
Shallow (Low Pressure)
Schematic Gravity Drainage
Gas Reservoirs
Gas Reservoir Drive Mechanism
Dominantly Depletion
Gas
Gas / Water
Contact
Coalbed Methane Production
Coalbed Methane Well (Oklahoma)
Multi-Phase Flow Issues
Gas
Oil
Water
American Petroleum Institute, 1986
“ D 6 “ HORIZONTAL WELLBORE TRAJECTORIES
LOWER D6 ( S 36 )
STRUCTURE
NET SAND
B-92
B-98
B-54
B-69
B-46
B-176
30
B-94
B-99
S.L.
S.L.
B-181
B-56
N
0
200
400
600
800
1000 M.
BADAK - 185 HORIZONTAL
SCHEMATIC WELLBORE STRATIGRAPHY
( VERTICAL EXAGGERATION = 20X )
7800
PILOT HOLE
8000
8200
8400
8600
8800
9000
9200
MEASURED DEPTH
TVD SS
-7090’
S 33
-7100’
~ OIL RIM UPPER LIMIT IN PILOT
-7110’
-7120’
B-184 PILOT
GOC
-7130’
S 36
BEGIN O/W TRANSITION ZONE IN PILOT
INITIAL TARGET
DEPTH
-7140’
-7150’
50 % Sw IN PILOT
Badak-185 Horizontal Lateral
(Elan Plus Interpretation)
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
Vertical Arbuckle Gas Well
COSTILOW - WILBURTON
1,002,828
802,828
Production Rates
602,828
Oil Production (bbl)
Gas Production (mcf)
402,828
202,828
2,828 Gas Production (mcf)
1988
1991
1994
1997
2000
Time
2003
2006
2009
Cum: 44.5 BCF
Vertical Coalbed Methane Well (Cherokee Platform)
ROSSON VERNON - HOLLOW NORTHWEST
4,137
Production Rates
3,137
Oil Production (bbl)
Gas Production (mcf)
2,137
1,137
137
1999
Gas Production (mcf)
2000
2001
2002
2003
2004
Time
2005
2006
2007
2008
Vertical Hartshorne Coalbed Methane Well
ARMY CORPS OF ENG - BROOKEN
25,253
20,253
Production Rates
15,253
Oil Production (bbl)
Gas Production (mcf)
10,253
5,253
Gas Production (mcf)
253
1983
1986
1989
1992
1995
1998
Time
2001
2004
2007
2010
Horizontal Hartshorne Coalbed Methane Well
DENNY - HASKELL COUNTY CBM GAS AREA
20,025
Production Rates
15,025
Oil Production (bbl)
Gas Production (mcf)
10,025
5,025
Gas Production (mcf)
25
2005
2006
2007
Time
2008
Vertical Woodford Gas Well
HAYNIE - AYLESWORTH DISTRICT SOUTHEAST
80,001
Production Rates
60,001
Oil Production (bbl)
Gas Production (mcf)
40,001
20,001
Gas Production (mcf)
1
1974
1978
1982
1986
(bbl)
1994 Oil Production
1998
2002
1990
Time
2006
2010
Horizontal Woodford Gas Well
PASQUALI - CHILES DOME
83,062
Production Rates
63,062
Oil Production (bbl)
Gas Production (mcf)
43,062
Gas Production (mcf)
23,062
2006
2007
Time
2008
Horizontal Woodford Gas Well
SHERMAN ELLIS - PINE HOLLOW SOUTH
Production Rates
397,827
Oil Production (bbl)
Gas Production (mcf)
297,827
Gas Production (mcf)
197,827
2007
2008
Time
Remedial work ?
Misener Oil Well
VANN C - PERRY
8,104
Production Rates
6,104
Oil Production (bbl)
Gas Production (mcf)
4,104
2,104
Cum: 670 MBO + 207 MMCF
Current Rate: 24 BOPD
Gas Production (mcf)
Oil Production (bbl)
104
1982
1985
1988
1991
1994
1997
Time
Approximately 240 MMCF Vented
2000
2003
2006
2009
Primary Recovery
Improving Recovery
Secondary (Waterflood)
Enhanced (Tertiary)
Producing Wells
Secondary
Recovery
Of 60% Remaining
in Reservoir
Water
Gas
Steam
Chemical
Fire
Injectio
n
Wells
Pumped into the
reservoir to force
additional petroleum
out of the pores in the
reservoir rock
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