Enhanced Oil Recovery-Slides-12

Tayfun Babadagli, PhD, PEng Short Course - EOR File-121

EOR IN NATURALLY FRACTURED RESERVOIRS


WHAT ARE THE DIFFERENCES BETWEEN “HOMOGENEOUS and FRACTURED RESERVOIRS?

•Fracture network controls the flow due to high k.•Matrix stores most of the oil due to high •Frontal advance theory may not be applicable.•Matrix-fracture interaction is the main cause of HC production

3

ELEMENTS OF NATURALLY FRACTUREDRESERVOIR MANAGEMENT

Characterization Reservoir dynamics EOR

Matrix FractureMost proper

methodMatrix effect

CoreWell testWell logsOutcrop

Experiment(Scaling)

Fracture effect

“Monitoring”performance

Numerical simulation


“HOMOGENEOUS” SYSTEMS

I I

I I

P

WATER BREAKTHROUGH

WATERPRODUCTION

I : INJECTION WELLP : PRODUCTION WELL

Swept ZoneUnswept Zone

Unrecovered oil can be in pores, never swept (not residual oil!!!!) OR it can be in pores swept (residual oil!!!!)


• UNSWEPT AREA: Channeling

FRACTURED SYSTEMS


EOR MECHANISMS in NFRs

• Fracture Recovery – Viscous Flow

• Matrix Recovery – Capillarity and Mass Transfer– Gravity Drainage

– Capillary Imbibition

– Convection

– Diffusion

7

OIL

WATER

X

x

a

aPgakq cow

o

oi

)(

Magnitude of gravity Magnitude of capillarity

OIL AND WATER

8

CONVECTION AND DIFFUSION

CONVECTION

•Result of contrasting oils within the fracture network•Large times are needed to see the effect of convection•High vertical permeability (fractures) accelerates•Oil at the crest is heavier than the base.•Vertical fractures provide communication for convection

DIFFUSION

•Contrast in HC properties between fracture and matrix

9

OIL

WATER

H

x

H-Z

])1([

)(

ZMMHkk

ZHgPu

rw

w

c

Z

High H and small Z Gravity dominates

Water wettability is small Gravity dominates

OIL-WATER : FULLY IMMERSED IN WATER

Z Height of the water front in the block above the bottom


6 min. 9 min. 12 min. 15 min.

0 20 40 60 80 100

Sw, Average

6 min.

30 min.

x, C

ore

Leng

th (v

ertic

al)

1

WAT

ER

WAT

ER

WAT

ER

WAT

ER

6 min. 9 min. 12 min. 15 min.


3 min. 18 min. 30 min. 1 day

0 20 40 60 80 100

Sw, Averagex, C

ore

Leng

th (v

ertic

al)

3 min

80 min.

0

1

OIL OIL OIL OIL

WAT

ER

WAT

ER

WAT

ER

WAT

ER

3 min. 18 min. 30 min. 1 day

Berea SandstoneHeavy Crude Oil-Brine

Indiana LimestoneLight Crude Oil -Brine

OIL RECOVERY IN NATURALLY FRACTURED RESERVOIRS

Capillary Imbibition Transfer at Static Conditions, i.e. No Flow of Water in Fracture

Matrix recovery by capillary imbibition is not EFFECTIVE if

• IFT is high• Unfavorable matrix boundary conditions restricting the contact of matrix and water in

fracture exist• Matrix is oil-wet

and• OIL VISCOSITY IS HIGH

PROBLEM

SURFACTANT, POLYMER, HOT WATER INJECTION

to reduce IFT and oil viscosityor to increase water viscosity

or to overcome unfavorable matrix boundary conditions and oil wettability

or to have additional recovery mechanisms

SOLUTION(Babadagli, Coll. And Surface A: Phys. And Eng. Asp., 2003 – SPE 69564)

?

EXPERIMENTATION AT STATIC CONDITIONS• Most proper EOR method (injection fluid)• Scaling to reservoir scale

OBJECTIVE

?

Which method (EOR fluid) yields the most effective recovery methods

different boundary conditions, oil type, IFT, oil viscosity, wettability.

PART I-ASELECTION OF EOR METHODS

for

0.1 1.0 10.0 100.0Time, minutes

10

30

50

0

20

40

60R

ecov

ery,

% O

OIP

T=26.5 °C

T=50 °C

T=80 °C

ENGINE-OIL (175 cP)

Unfired Berea

0.1 1.0 10.0 100.0 1000.0Time, minutes

10

30

50

70

0

20

40

60

80R

ecov

ery,

% O

OIP

% 1 SURFACTANT (IFT=6 dyn/cm)

% 2 SURFACTANT (IFT=5 dyn/cm)

BRINE (IFT=41 dyn/cm)

MINERAL OIL (235 cP)

Unfired Berea

ROCK & FLUID PROPERTIES

OILKerosene

Crude Oil (light)Engine oilMineral Oil

SURFACTANT1 vol %

POLYMER0.1 and 0.2 wt %

Rock type : Unfired BereaLength : 10 cm.Diameter : 3.8 and 2.5 cm.Permeability : 500 md.Porosity : 0.2Brine : 3 wt % NaCl

20

FLUID PROPERTIESFLUID TYPES

Densityg/cc

ViscositycP

IFT with

kerosene dyne/cm

IFT with

crude oil dyne/cm

IFT with

engine oildyne/cm

Brine (3% NaCl)

1 1.1 40 25 71

Surfactant Solution (1%)

1 1.1 11 11 15

Surfactant Solution (2%)

1 1.1 - - 14

Polymer I (0.1 wt %)

1 18 - 17 23

Polymer II (0.2 wt %)

1 87 - 22 24

Kerosene 0.79 1.7

Crude Oil 0.81 5.6 Engine Oil 0.89 633

COUNTER-CURRENT IMBIBITION (CCI)

Open Matrix SurfaceCoated Matrix Surface

(CCI)(CCI) (CCI)

(Babadagli, Coll. And Surface A: Phys. And Eng. Asp., 2003 – SPE 69564)

CO-CURRENT IMBIBITION (CCI)

Open Matrix SurfaceCoated Matrix Surface

(CCI)

(CCI)

(CCI)


OIL

Coating

WATERMovement of waterMovement of oil

Oil saturated rock (Berea SS)

Capillary imbibition(water in oil out)

Gravity (oil up water down)

Capillary re-imbibition(oil down water up)

DIFFERENT OIL WATER BOUNDARY CONDITIONS by COATING (CO-CURRENT FLOW)

INVERSE BOND NUMBER

N = cg H

kB

-1

Capillarity

Gravity

NB-1 > 5 NB

-1 < 0.25 > NB-1 > 0.2

R RR

log(t) log(t) log(t)

REPRESENTATIVE RECOVERY CURVESSchechter et al. 1994

KEROSENE - COUNTER-CURRENT IMBIBITION

0102030405060

0.01 0.1 1 10 100 1000 10000Time, minutes

Oil

Rec

over

y, %

OO

IP

Kerosene-Brine Kerosene-Surfactant

BOUNDARY CONDITIONS



27

0

10

20

30

40

50

60

0.01 0.1 1 10 100 1000Time, minutes

BrineSurfactant (1 vol %)O

il R

ecov

ery,

% O

OIP

BC: COU-C1 Oil Type : Crude Oil Core Diameter = 1.5 in.



28

0

10

20

30

40

50

60

1 10 100 1000 10000 100000

Time, minutes

Brine

Surfactant (1 vol %)Oil

Rec

over

y, %

OO

IPOil Type : Crude Oil Core Diameter = 1.5 in.


STATIC CONDITIONSCapillary Imbibition Transfer at Static Conditions,

i.e. No Flow of Water in Fracture


30

0

10

20

30

40

50

60

0.01 0.1 1 10 100 1000 10000 100000Time, minutes

BrineHeat (40 C)Heat (80 C)O

il R

ecov

ery,

% O

OIP

Oil Type : Crude Oil Core Diameter = 1.5 in.



31

0

10

20

30

40

50

60

0.01 0.1 1 10 100 1000 10000 100000 1000000Time, minutes

BrinePolymer (0.1 wt %)Polymer (0.2 wt %)O

il R

ecov

ery,

% O

OIP

Oil Type : Crude Oil Core Diameter = 1.5 in.



32

0

5

10

15

20

25

30

100 1000 10000 100000 1000000Time, minutes

BrineTemp. increased to 80 CSurfactant ( 1 vol %)Surfactant (2.5 vol %)O

il R

ecov

ery,

% O

OIP

Oil Type : Engine Oil Core Diameter = 1 in.



33

0

5

10

15

20

25

30

1 10 100 1000 10000 100000 1000000Time, minutes

BrineTemp. increased to 80 CBrine (40 C)Temp. increased to 80 CBrine (80 C)

Oil

Rec

over

y, %

OO

IPOil Type : Engine Oil Core Diameter = 1 in.



34

Berea Sandstone, Oil Type : Heavy Crude Oil (2200 cP) Core Diam. = 1 in.

0

10

20

30

40

50

60

70

1 10 100 1000 10000 100000 1000000

Time, min.

Brine-Heavy Crude Oil

Polymer-Heavy Crude OilSurfactant-Heavy Crude Oil

Hot Water-Heavy Crude Oil

Oil

Rec

over

y, %

OO

IP

(Babadagli, CIPC, 2001-130, 2001


35

Berea Sandstone, Oil Type: Heavy Crude Oil (2200 cP)Core Diam.= 1.5 in.

0

5

10

15

20

25

30

35

40

45

50

1 10 100 1000 10000 100000 1000000

Time, min.

Brine-Heavy Crude Oil

Hot Water-Heavy Crude Oil

Oil

Rec

over

y, %

OO

IP



36

Indiana Limestone, Oil Type : Heavy Crude Oil (2200 cP) Core Diam. = 1 in.

0

1

2

3

4

5

6

7

8

9

1 10 100 1000 10000 100000 1000000

Time, min.

Brine-Heavy Crude OilPolymer-Heavy Crude OilSurfactant-Heavy Crude OilHot Water-Heavy Crude Oil

Oil

Rec

over

y, %

OO

IP



37

0

2

4

6

8

10

12

14

16

1000 10000 100000 1000000Time, minutes

Brine, k=276 mD Polymer (0.1 wt %), k=128 mDPolymer (0.2 wt%), k=155 mD Surfactant (1 vol %), k=19 mDSurfactant (2.5 vol %), k=24 mD Heat (40 C), k=1 mDHeat (80 C), k=4 mD Temp. increased from 40 to 80 C

Oil

Rec

over

y, %

OO

IP

DOLOMITIC LIMESTONE


- Light oils: no surfactant. Especially for unfavorable BC.- Heavy oils: surfactant is desirable. Especially for

unfavorable BC.- Light oils: polymer is not desirable. For all BCs.- Heavy oils: polymer is desirable. Especially for

unfavorable BC.- Thermal is effective to fasten light oil recovery but not

for ultimate recovery.- Thermal is effective to fasten heavy oil recovery and for

ultimate recovery.

SELECTION CRITERIASANDSTONES

- They all good!- Thermal > surfactant > polymer > brine.

SELECTION CRITERIACARBONATES

Enhanced Oil Recovery-Slides-12

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