Carbon Dioxide Demonstration Project Supporting Research at KU

1
Carbon Dioxide Demonstration Project Supporting
Research at KU

• Jyun-Syung Tsau
• presented for
• Tertiary Oil Recovery Project
• Advisory Board Meeting
• October 19-20, 2001

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Supporting Research Activities

• Simulation
• Hall-Gurney field (LKC formation)
• Bemis-Shutts field (Arbuckle formation)
• Laboratory experiments
• Slim-tube displacement
• Residual oil measurement

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Simulation

• Reservoir simulator
• VIP black oil simulator
• Primary production, waterflooding
• VIP compositional simulator
• CO2 flooding

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Compositional Simulator

• Equation of state (EOS) for CO2-oil phase
  behavior characterization and properties
  calculation
• Peng-Robinson 3-parameter EOS model

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Typical Data Preparation for Compositional
Simulation

• C7 characterization (sub-grouping heavy end)
• Pseudoization (grouping)
• Phase behavior calculation (swelling test)
• Slim-tube displacement

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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

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Schematic of Slim-tube Experiment Apparatus
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Oil Recovery Performance in Slim-tube
Experiment(Letsch 7 oil)
Temp 105 F
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MMP Measurements of Letsch 7 Oil
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Oil Recovery Performance Match
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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

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Critical Issues to the Measurements

• Measurement needs to account for
• Well defined development of miscibility
• Representative fluid and rock properties

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Schematic of Residual Oil Saturation Measurement
Apparatus
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Characteristics of Slim-tube and Core Sample
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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

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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

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MMP Measurements of Peavey B1 Oil (Bemis-Shutts
field)
Temp 108 F
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Current Reservoir Condition

• Average reservoir pressure is around 500 psia,
  which is not high enough for CO2 miscible
  displacement
• Reservoir must be pressurized

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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)

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Grid Cell System Used in the Model
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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

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Satisfactory Match

• Simulation results were to match
• Reservoir average pressure
• Cumulative oil and water production
• Current oil and water production rate

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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

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Pressure Distribution at the End of Primary
Production (Beginning of Pressurization)
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Simulation Tests to Pressurize a Project Area

• 5 spot pattern (10 acres) with 6 confining
  injectors (within 120 acres)

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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

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Pressure Distribution After 3-years
Pressurization
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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.

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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

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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