Simulation of CO Exsolution for Enhanced Oil Recovery and ...

Simulation of CO2 Exsolution for Enhanced Oil Recovery and CO2 Storage

By Scott McLaughlin

S TAN F O R D C EN TER F O R C AR BO N S TO R A G E A N N U AL

M EET I N G

M AY 11 , 2 0 1 6

Contents

Background – Laboratory work

Exsolution at the pore and core scales

Experimental oil recovery with CO2 exsolution

Reservoir Simulation of CO2 Exsolution

TOUGH2 two-phase simulations

Eclipse three-phase simulations

Conclusions

2

Background

C O 2 E X S O L U T I O N I N T H E

L A B O R A T O R Y

4

Background – CO2 Exsolution

Mobility Control

Carbonated brine injection followed by CO2 liberation through

depressurization under immiscible conditions

Provides mobility control from strong capillary trapping and relatively

small length of connected gas phase that could improve efficiency of

water flooding

Other Benefits

CO2 sequestration

Viscosity reduction

4[Zuo 2013]

5

Mobility Control Alters Water Flow Paths and Enhances Recovery

[Zuo 2014]

Flow path WaterCO2Oil

5

6

Low Relative Permeability of Exsolved CO2-Water System

Berea Sandstone Mt. Simon Sandstone

[Zuo 2014] 6

7

Improvement in Recovery Factors in Cores from Carbonated Brine Injection with CO2 Exsolution

[Zuo 2014][Alizadeh 2014]

7

Simulation of CO2Exsolution and Oil

Recovery

T W O - P H A S E A N D T H R E E -

P H A S E S I M U L A T I O N S

Is there a practical way of implementing CO2 exsolution enhanced oil

recovery on a reservoir scale?

Questions to Answer Using Reservoir Scale Simulations

Two-phase Flow Simulation

What are the time and spatial scales for which we can exsolve CO2

through depressurization at the reservoir scale?

Three-phase Flow Simulation

How does carbonated water injection and CO2 exsolution affect oil

recovery?

What are the primary mechanisms affecting recovery enhancement?

Does the importance of mobility control depend on oil properties?

9

10

Simulation Model for Two-Phase Flow

TOUGH2 two-phase flow

2D homogenous cross-

section model with log-

spaced grid in x-direction

Initially brine that is

saturated with CO2

ECO2N EOS (water,

NaCl, CO2)

Relative permeability by

van Genuchten-Maulem

model fit for exsolution1000m

50m

Gas Saturation

Producer

10

11

Two-Phase Flow Results

Need confined reservoir or

confining well pattern to

achieve depressurization

throughout reservoir

CO2 exsolution achieved

throughout 1km confined

reservoir

Production rate limited by

clogging effect

Increasing

Production

Increasing

Production

11







recovery?



12

Simulation Model for Three-phase Flow

ECLIPSE CO2SOL

2D heterogenous model

200x1x20 grid cells (1524 meters by 7.6 meters by 15 meters)

Initially fully oil saturated with connate water

Isothermal at 65C, initial pressure 100 bar

Injector Producer

13

Binned Groups for Capillary Heterogeneity

0

0.2

0.4

0.6

0.8

1

0.001 0.01 0.1 1 10 100 1000

Cu

mu

lati

ve F

req

uen

cy

Permeabiity (md)

Permeability CFD - 2001 SPE Comparative Solution Project

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

0 0.2 0.4 0.6 0.8 1

Pc (

Bar

)

Sw

Brine/CO2 Capillary Pressure (Berea Sandstone)

Group 1

Group 2

Group 3

Group 4

Group 5

1 2 3 4 5

𝑃𝑐 = 𝑃𝑒𝑆𝑤 − 𝑆𝑤𝑖

1 − 𝑆𝑤𝑖

−1λ

𝑃𝑒 = 𝑃𝑒𝑟𝑒𝑓𝑘𝑟𝑒𝑓𝑘

14

Exsolution Relative Permeability

Two-phase relative permeabilities

from experimental data for exsolved

CO2-water

Baker method to generate 3-phase

Kri =Sj− Sjc Krij + Sk− Skc Krik

Sj− Sjc + (Sk− Skc)

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

Kr

Sw

Krwo (Sw)

Krw

Kro

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

Kr

Sw

Krwg (Sw)

Krw

Krg

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

Kr

So

Krog (So)

Kro

Krg

15

Four Cases and Production Strategy

Four different oil types ranging from heavy to light oil

Production Strategy:

1) Primary Recovery

2) Water Flood

3) Carbonated Water Flood

4) Depressurization and Carbonated Water Flood

CaseAPI

GravityDensity (kg/m3)

Viscosity (cP) MW

Pc (bar) Tc (K) ω

1 10 980 1000 405 15.2 933 0.9

2 20 915 165 320 16.5 844 0.7

3 30 859 27 242 18.6 756 0.6

4 40 809 4.5 192 20.7 700 0.5

16

Case 2: API 20 CO2 Exsolution Enhanced Oil Recovery

Step 1: Primary Recovery – 0.002 Recovery Factor

Step 2: Water Flood (0.4 PVI) – 0.22 Recovery Factor

Oil Saturation Water Saturation

Oil Saturation Water Saturation

17

Case 2: API 20 CO2 Exsolution Enhanced Oil Recovery

Step 3: Carbonated Water Flood (1 PVI) – 0.34 Recovery Factor, 0.91 WCT

Step 4: Depressurization and Carbonated Water Flood (1 PVI) – 0.49 RF, 0.82 WCT

Water SaturationOil Saturation

Oil Saturation Gas Saturation

18

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.5 1 1.5 2 2.5

Re

co

ve

ry F

acto

r

PVI

Recovery Factor vs Pore Volume Injected for API 20 Oil

Water Flood

Case 2: Recovery Factor is Highest by Exsolution

Water

Flood

19

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.5 1 1.5 2 2.5

Re

co

ve

ry F

acto

r

PVI


Carbonated Water Flood

Water Flood


Water

Flood

Carbonated

Water Flood

20

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.5 1 1.5 2 2.5

Re

co

ve

ry F

acto

r

PVI


Exsolution


Water Flood


Water

Flood

Carbonated

Water FloodPressure Drop

21







recovery?



20

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.5 1 1.5 2 2.5

Re

co

ve

ry F

acto

r

PVI


Exsolution

Brooks-Corey


Water Flood

Case 2: Recovery Improvement Partly Due to Mobility Control and Partly Due to Viscosity Reduction

Water

Flood

Carbonated

Water Flood Pressure Drop

21







recovery?



22

Mobility Control Mechanism More Important for Recovery of Heavier Oil

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

Rec

ove

ry F

acto

r

PVI

Recovery Factor vs Pore Volumes Injected for Different Oils

Brooks-Corey

Exsolution

API 40

WaterFlood


Pressure Drop

API 30

API 10

API 20

23

Conclusions

Exsolution of CO2 by depressurization achievable with confining well

pattern or confined reservoir

24

Conclusions



Carbonated water injection leads to enhancement in oil recovery

24

Conclusions



Carbonated water injection leads to enhancement in oil recovery

For intermediate to heavy oils mobility control of wetting phase by

exsolved CO2 provides significant improvement in oil recovery

24

Questions?

Solubility of CO2 in Water and API 20 Oil with Pressure

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

0 20 40 60 80 100 120 140 160

kg/k

g

Pressure (Bar)

Phase Behavior of CO2 in Water and Oil with Pressure

Mass fraction CO2 in Water

Mass fraction CO2 in Oil

Initial

Condition

Final

Condition

Location of Exsolved CO2

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

1.00E-031.00E-021.00E-011.00E+001.00E+011.00E+021.00E+03

Gas S

atu

ration

Permeability (md)

API 40 Gas Saturation vs Permeability

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 1.00E+02 1.00E+03

Gas S

atu

ration

Permeability (md)

API 20 Gas Saturation vs Permeability

Simulate Immiscible Recovery for Light to Heavy Oils

Evaluated recovery for a variety

of oils with different viscosities

and densities

Correlations used to obtain

realistic values for oil properties

[Verma 2015]1

10

100

1000

10000

100000

0 10 20 30 40 50

Vis

cosi

ty (

cp)

API Gravity

Viscosity vs API Gravity of Crude Oils

Heavy

Light

Initial ConditionAPI 10

API 20

API 30

API 40

Simulation of CO Exsolution for Enhanced Oil Recovery and ...

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