Carbon Dioxide Demonstration Project Supporting Research at KU Jyun-Syung Tsau presented for...
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Carbon Dioxide Demonstration Project Supporting Research at KU
Jyun-Syung Tsau
presented for
Tertiary Oil Recovery Project
Advisory Board Meeting
October 19-20, 2001
Supporting Research Activities
• Simulation– Hall-Gurney field (LKC formation)– Bemis-Shutts field (Arbuckle formation)
• Laboratory experiments– Slim-tube displacement– Residual oil measurement
Simulation
• Reservoir simulator– VIP black oil simulator
• Primary production, waterflooding
– VIP compositional simulator• CO2 flooding
Compositional Simulator
• Equation of state (EOS) for CO2-oil phase behavior characterization and properties calculation
• Peng-Robinson 3-parameter EOS model
Typical Data Preparation for Compositional Simulation
• C7+ characterization (sub-grouping heavy end)
• Pseudoization (grouping)
• Phase behavior calculation (swelling test)
• Slim-tube displacement
Laboratory Displacement Data to Fine Tune Reservoir Simulator
• Slim-tube displacement experiment– Ideal porous media– Oil recovery attributed to phase behavior– MMP (minimum miscibility pressure)
indicates the pressure required to develop multiple-contact miscibility
– Fine tune EOS parameters in reservoir simulator
Schematic of Slim-tube Experiment ApparatusC
O2
sour
ce
Milton Roy pump
Effluent
N2 source
CO
2
Oil
T
TT
ISCO pump
ISCO pump
BPR
T
Oil Recovery Performance in Slim-tube Experiment(Letsch #7 oil)
0
0.2
0.4
0.6
0.8
1
0.0 0.2 0.4 0.6 0.8 1.0 1.2CO2 injection (HCPV)
Oil
pro
du
ced
(H
CP
V)
1305 psia
1015 psia
Temp: 105 °F
MMP Measurements of Letsch #7 Oil
40
50
60
70
80
90
100
800 900 1000 1100 1200 1300 1400
Pressure (psia)
Rec
ove
ry (
%)
Recovery at 1.0 HCPV CO2 injection
Oil Recovery Performance Match
0
0.2
0.4
0.6
0.8
1
1.2
0.0 0.5 1.0 1.5 2.0
CO2 injection (HCPV)
Oil
pro
du
ced
(H
CP
V)
Experiment
Simulation_bip0.05
Simulation_bip0.0735
Pressure = 1305 psia
Determination of Residual Oil Saturation to Carbon Dioxide
Why it is important?
• Miscibility developed by multiple contact results in variable amount of oil left behind in CO2-swept zone
• Uncertainty in projection of oil recovery by the simulator
Critical Issues to the Measurements
• Measurement needs to account for
– Well defined development of miscibility
– Representative fluid and rock properties
Schematic of Residual Oil Saturation Measurement Apparatus
Characteristics of Slim-tube and Core Sample
Slim-tube Core sampleLength (inch) 459.48 1.9205
I.D. (inch) 0.2425 0.9845
Bulk volume (cc) 347.80 23.96
Pore volume (cc) 127.76 5.26
Porosity (%) 36.73 21.95
Permeability (md) 4900 453.73
Porous media Glass bead Berea sandstone
Future Tasks
• Investigate the effect of displacement rate, core length and structure on residual oil saturation determination
• Investigate the effect of water saturation on the residual oil saturation to CO2
Evaluation of Arbuckle Crude Oil for Oil Recovery by CO2 Displacement
• Conduct experiment to measure MMP of crude oil obtained from Arbuckle formation
• Perform simulation to match current field condition and test the reservoir response to pressurization process
MMP Measurements of Peavey #B1 Oil(Bemis-Shutts field)
40
50
60
70
80
90
100
800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800
Pressure (psia)
Oil
reco
very
(%
OO
IP)
Temp: 108 °F
Current Reservoir Condition
• Average reservoir pressure is around 500 psia, which is not high enough for CO2 miscible displacement
• Reservoir must be pressurized
Approaches
• Construct a generic model to simulate the process of– Primary production– Pressurization
• Model contains– 126 active production wells in a 2 by 2
square miles area (2560 acres)
Grid Cell System Used in the Model
Cross Section of the Reservoir Formation
• 11 layers with permeability ranging between 0.2 ~5 md in aquitard and 50 ~1500 md in production zones
86 ft
2 miles
aqui
feraquitard
3486'
3400'
Satisfactory Match
• Simulation results were to match– Reservoir average pressure– Cumulative oil and water production– Current oil and water production rate
Observations
• Reservoir is a layered reservoir with high permeability contrast between layers
• Bottom water drive
Edge water drive does not provide enough energy to support the average reservoir pressure and production performance
Pressure Distribution at the End of Primary Production (Beginning of Pressurization)
Simulation Tests to Pressurize a Project Area
• 5 spot pattern (10 acres) with 6 confining injectors (within 120 acres)
Well Condition Parameters During the Pressurization
• Injector– 5-spot: BHP: 2000 psia, Qmax: 3000 bbl/day– Confining area: BHP: 2000 psia, Qmax: 3000
bbl/day
• Producer– 5-spot: shut-in– Around confining area: BHP: 1100 psia, Qmax:
300 bbl/day– Other active producers : BHP: 300 psia, Qmax:
300 bbl/day
Pressure Distribution After 3-year’s Pressurization
Summary of Pressurization Process
• The magnitude of pressure increase within a pattern depends on the size of the pattern, confining area, and bottom hole pressure control of injectors and producers.
• The ultimate pressures within the pattern varied from 1200 psia to 1500 psia.
Preliminary Results
• Attainable reservoir pressure might slightly below the MMP as required for a miscible CO2 displacement
• Oil recovery remains relatively high (70 ~85%) for a few hundred psi below MMP
Current Status
• Oil and gas samples collected from the wellhead and separator were analyzed by Core-Lab
• High nitrogen content was found on some of the separator samples through the quality check, which suggests the needs to measure MMP and oil recovery using a live oil sample
• Detailed PVT test and swelling test would be conducted by Core-Lab, and data would be used for compositional simulation