Advances in CO2 EOR Reservoir Modelling

公开课第12课

CO2提高采收率数值模拟进展

Agenda

• Introduction to EOR Processes

• Design Steps of CO2 EOR

• Mechanism Important to Process

• Advances in Hybrid EOR Processes

• Practical Workflow & Case Studies

• Conclusions

Why EOR Processes?

Oil recoveries from primary and secondary recovery phases are generally in the range of 20–40% of OOIP

Little Creek Field

Why CO2 EOR?

Two major advantages: • Additional oil recovery

• CO2 storage to reduce emissions of CO2

Miscible or Immiscible CO2 EOR?

• Proven to be technically feasible in miscible andimmiscible modes

• Among 123 CO2-EOR projects in the United States, 114are miscible projects (koottungal, 2012; kuuskraa, 2012)

• Mainly on light to ultra-light oils (>28°API) with aviscosity of less than 3 centipoise

Design Steps of CO2 EOR

Data Management and Analyses

Screening

Experimental Studies

Detailed Studies

Project Feasibility

Field Pilot Implementation

Full Field Development

Reserves (e.g. OOIP)Petro-physical Properties Oil Price, etc.

Criteria (e.g. depth)Projected Recovery Requirements, etc.

Full PVT ExperimentsCore Flood TestsRecovery Mechanisms, etc.

Risks (Enviro. & Tech.)Comm. & Political factors, etc.

Simulation Model

Applicability,Potential, Economic

Performance Monitoring

Optimization using Simulation

What Does Reservoir Modelling Aim at?

Better Understanding of Reservoir Performance

Steps to Make a Representative Model?

STEP 1: Reliable data Input • Reservoir Parameters, PVT, etc.

STEP 2: History Matching• Production and pressure history data

STEP 3: Forecast• Different scenarios, optimum design, etc.

Most Important StepNeeds understanding of physics and important

mechanisms

Reliable and Capable Modelling Tool

CO2 EOR Mechanisms

• PVT, solubility, and swelling

• Miscibility mechanisms

• Asphaltene deposition

• Wettability Alteration

• Hysteresis

• IFT Effects

• Diffusion and Dispersion

Additional Process Mechanisms

• Matrix dissolution from CO2 injection

• Aqueous chemical equilibrium reactions

• Ion-exchange

• Mineralization: dissolution and precipitation

• Thermal effects

• CO2 leakage through caprock

What to Use?

• Advanced general equation-of-statecompositional simulator

• Simulates compositional effects ofreservoir fluid during primary andenhanced oil recovery processes

• Phase behaviour and reservoir fluidproperty program for PVT modellingand data matching

For modelling of:

• Gas condensates

• Tight/shale gas

• CO2 EOR

• WAG

• Chemical EOR

• CO2 Sequestration

• LSW flooding

• Polymer Flooding

• ASP flooding

• D

Sensitivity Analysis

• Better understanding of a simulation model• Identify important parameters

History Matching

• Calibrate simulation model with field data• Obtain multiple history-matched models

Optimization

• Improve NPV, Recovery, D• Reduce cost

Uncertainty Analysis

• Quantify uncertainty• Understand and reduce risk

What to Use?

PVT

• Fluid Characterization

‒ Compositional Analysis

‒ Recombination

• Lab Data Matching

→→→→ P, T, and composition variation

‒ CCE

‒ Differential liberation

‒ Separator test

‒ Swelling test

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a)

CO2 Composition

ModelExp. Data

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Gas-O

il R

ati

o (

sm

3/s

m3)

Pressure (kPa)

Model

Exp. Data

Define pseudo-comp.

Miscibility Mechanisms

• Vaporizing, condensing, combined

• MMP and MME determination

• Methods‒ Cell to Cell ‒ Multiple Mixing Cell ‒ Semi-Analytical

Solubility in Water

• Direct Henry’s ConstantInput

• Correlations‒ Harvey’s Method

‒ Li-Nghiem’s Method

‒ Account for Salinity

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ula

ted

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2 S

olu

bilit

y (

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le f

racti

on

)

Experimental CO2 Solubility (mole fraction)

Nighswander et al. (1989)

Kiepe et al. (2002)

Lucile et al. (2012)

Asphaltene Precipitation

Change in P, T, or Composition• Asphaltene/Wax Modelling Native Oil Solvent (CO2)

Precipitation

Flocculation

DepositionRe-Entrainment Pore Plugging

DepositionFlocculation

Pre

cip

itatio

n

Flocculation and Deposition

Plugging and Permeability Impairment

• Flocculation

‒ Aggregation into larger particles

‒ Suspended component

• Deposition

‒ Surface deposition, plugging deposition and re-entrainment

‒ Non-equilibrium Blockage

Blockage

• Resistance Factor Calculation‒ Power Law Model

‒ Kozeny-Carman Equation

‒ Solid Adsorption Model

• Permeability is divided by theresistance factor whilecalculating the phasetransmissibilities

k = k0 / rf

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Pore Volumes Oil Injected

Pe

rme

ab

ilit

y R

ed

uc

tio

n (

k/k

0)

Experiment Model

Leontaritis et al. 1994, SPE 23810.

Wang 1988, SPE 37232

Wettability Alteration

• Wettability alteration− Asphaltene adsorption

− Geochemical interaction/ionexchange

• Capillary pressure andrelative permeability curveschange* KRINTRP

* INTCOMP

IFT Effect

• Relative permeability as a function of IFT

• At higher IFT, typical relative permeability curves

• Straight line relative permeabilitiesas the IFT is lowered

CO2 CO2

Nearly Miscible

Zone

Oil Bank

Additional Oil

Water Water

Hysteresis

A fluid (e.g. gas) moves into a pore:

1) Displaces fluid in pore(called drainage)

2) Sometimes displaced fluidmoves back into the pore(called imbibition)

3) A shift in the RelativePermeability during this can trapsome of the gas in the pore,making it immobile

Videos Courtesy Laboratório de Meios Porosos e Propriedades Termofísicas

Hysteresis

A fluid (e.g. gas) moves into a pore:

1) Displaces fluid in pore (called drainage)

2) Sometimes displaced fluid moves back into the pore (called imbibition)

3) A shift in the Relative Permeability during this can trap some of the gas in the pore, making it immobile

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lati

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rme

ab

ilit

y t

o G

as

Gas Saturation

Relative Permeability to Gas Changes Due to Hysteresis

Trapped due to Hysteresis

Diffusion and Dispersion

*D

D

*p D/du

Hydrostatic axis (σ’1= σ’2= σ’3)

σ’1, σ’2, σ’3 : Principle effective stresses

Cap

σ’1

σ’2

σ’3

Hydrostatic axis (σ’1= σ’2= σ’3)

σ’1, σ’2, σ’3 : Principle effective stresses

Cap

σ’1

σ’2

σ’3

Geomechanics

• Caprock integrity due to stress/strain relationships

• Different constitutive models

• Applications:

− Risk assessment in sequestration

− Deformation of geological structure due to fluid withdrawal/injection

− Geomechanical effects on coal-seams

− D

Geomechanics

Perkins and Johnston 1963

Advances in Hybrid EOR Processes

LSWI, Foam, etc.

CO2 + Low Salinity Water Flooding

LSW is attractive because:

• Operationally identical to conventional waterflooding

• No requirements for expensive chemicals

• Possible significant increase in recovery

LSW works in oil-wet reservoirs with clay

Main mechanism: wettability change from oil-wet to water-wet

CO2 LSWAG

CO2 WAG

- CO2 Miscibility

- Mobility Control (WAG)

- High Recovery Factor

- Delayed Production Problem

LSWI

- Wettability Alteration

- Higher Recovery w.r.t HSWI

- Lower Chemical Cost

- Environmental Impact

- Field Implementation

- Lower Recovery w.r.t Miscible Floods

CO2 LSWAG

- Synergy of Mechanisms

- CO2 Miscibility

- Mobility Control

- Wettability Alteration

- Geochemical Reaction with Inj CO2

- Ion Exchange

- Dissolution of Carbonate Minerals

- Higher Recovery w.r.t HSWI, LSWI, CO2 HSWAG, and pure CO2

- No Challenge of late Production

CO2 LSWAG in GEM

• EOS compositional simulator

• Full geochemistry model

− Aqueous reactions E.g. CO2(aq) + H2O = (H+) + (HCO3-)

− Ion exchange equilibria E.g. (Na+) + 0.5(Ca-X2) = 0.5(Ca++) + (Na-X)

− Mineral dissolution/precipitation reactions E.g. Calcite + (H+) = (Ca++) + (HCO3-)

• Interpolation between oil-wet andwater-wet relative permeability based onion exchange

• Models temperature effects on low salinity

Foam Assisted CO2 EOR

• Gas Mobility Control – Improve the sweep efficiency in by-

passed oil zones– Foam is used to change the mobility of

gas in the reservoir

• Gas Shut-Off – Foam around perforations reduce gas

mobility and production in wells located near the gas oil contact

Advances in Foam Modelling

• FMMOB: Foam Mobility

• F1: Surfactant Concentration

• F2: Oil Saturation

• F3 & F4: Capillary Number

• F5: Oil Composition

• F6: Salinity

• FDRY: Foam Dry Out

Modification of Relative Permeability Dependencies

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• Uses FM as interpolant

– FM = 0 Strong Foam

– FM = 1 No Foam

• Use FM as a multiplier to krg

Practical Workflow

Practical Work Flow

PVT Modelling

GEM 1D Model

Geological Modelling

Reservoir SimulationFlow, Wettability

Alteration, Miscibility, D

Sensitivity AnalysisHistory Matching

OptimizationUncertainty Assessment

CCE, Diff Liberation Separator, Swelling Test, D

Slim tube, Core-floods, D

Case Studies

Case Studies

Case 1: Field-scale inverted 5-spot pattern model• Application of workflow

Case 2: Field scale model • Primary and Secondary Recovery HM• WAG optimization• Evaluation of Mechanisms

Case 1: Field-Scale 5-spot Model

CCE Diff Lib

Separator

Fluid Model

Swelling testSaturated µ , ρ

FCM, Oil/CO2 Model

Slim Tube Test

Thermodynamic

Models (MCM)1D Model

Oil Recovery

Core Flood

1D ModelWAG

SS & HMRel Perm

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Check MMP - Cell to Cell- Multiple Mixing- Semi-Analytical

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al

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ula

tor

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ta

Case 1: Field-Scale 5-spot Model

Geological data, maps, etc

Base Case

Primary Production

Data

Prod & Press HM

Forecast

Optimization

TT1

Time (Date)

Oil R

ate

SC

(b

bl/d

ay)

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ut

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Case 2: Field Scale Model

Original Oil in Place (OOIP):684.6 million barrels

• Start with 7 years of primary production (1983-1990)

• Followed by 18 years of water-flooding (1990-2008)

• Water-flooding followed by CO2 WAG process from 2008-2035

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illi

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Time01/01/1983 23/06/1988 14/12/1993 06/06/1999 26/11/2004 19/05/2010

Case 2: Multiple-Stage History Match

Needed to match• Bottom-hole

pressures

• Cumulative oil production

− Per well

− Entire field

• From 1983 - 2008

Initial History Match (Primary)

Secondary History Match (Water-Flood)

CO2 EORPrediction

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Simulator Run Number

Net-

Pre

sen

t V

alu

e (

Mil

lio

ns $

)

700

775

850

925

1000

Base Solution, $750 Million

Optimized Solution, $975 Million

Case 2: Optimization of WAG Process

Optimized NPV

– Base NPV• $750 Million

– Optimized NPV• $975 Million

– Slug sizes

– Injection pressures

– Producer water-cut& GOR controls

Case 2: Physics Included

EOS phase behaviour

• Correctly accounts for phase changes of oil and CO2

FCM and MCM determinations

• Viscosity alteration

Solubility of CO2 in the aqueous phase

• Viscosity and density alterations of aqueous phase

Case 2: Additional Considerations

HysteresisNative Oil Solvent (CO2)

Precipitation

Flocculation

DepositionRe-Entrainment Pore Plugging

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lid

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itati

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3%5%

Asphaltene Deposition

GEM

– Geochemical EOS compositional simulator for CO2 storage in saline aquifers

Modelling of CO2 solubility and brine properties

– Solubility trapping

Relative permeability hysteresis

– Residual gas trapping

Aqueous chemical equilibrium reactions and mineral dissolution and precipitation kinetics

– CO2 mineralization

Geo-mechanics to model the cap rock integrity based on stress/strain relationships

Capabilities for Carbon Management

Conclusions• CMG accurately models CO2 related processes and mechanisms

• PVT modelling and data matching (WinProp)

• GEM multiphase multicomponent EOS thermal flow simulator

− CO2 Flooding, WAG, Foam, Polymer, ASP, LSWI, D

− Low Salinity + Miscible + Foam + ASP

− GEM is only commercial simulator that models combination of processes

• Full geochemistry model (aqueous reactions, ion-exchange, mineraldissolution, D)

• Geomechanics Module

• Sensitivity study, history matching, optimization, uncertainty analysis(CMOST)

• No other simulator/package can do all of this!