Group PresentationOctober 2002 Fluid Flow Through The Fracture under Different Stress-state Condition Vivek Muralidharan Dicman Alfred Dr. Erwin Putra

Group Presentation October 2002

Fluid Flow Through The Fracture under Different Stress-state

Condition

Vivek MuralidharanDicman AlfredDr. Erwin Putra

Dr. David Schechter


CORE HOLDER PERMEAMETER

HYDRAULIC JACK

Matrix4.98 Cm

A=4.96 Cm2

Fracture

Graduated Cylinder

Accumulator 1 Accumulator 2

PUMP 1 PUMP 1

Graduated Cylinder

BLACK

RED

Schematic of Experiment Apparatus


Pob psia

Dp psia

km md

Q Cm3/m

485.7 4.1 299.7 5 506.4 8.1 303.4 10 502.9 12.4 297.2 15 504.4 16.5 297.85 20 501 4.2 292.5 5

504.9 8.5 289 10 501 13 283 15 502 17 289.1 20

1000.4 4.5 273 5 1002.4 9 273 10 1000.5 13.7 269 15 1000.5 18.2 270 20 1000.2 4.8 255.9 5 1003.5 9.7 253.3 10 1002.7 14.5 254.2 15 1004.1 19.2 255.96 20 1500 5.1 240.8 5 1500 10.4 236.3 10

1500.7 16.4 224.7 15 1503.1 22.1 222.4 20 1500.3 5.5 223.4 5 1501 11.2 219.4 10

1501.3 17.3 213 15 1502.3 22.7 216.5 20

Pob psia

Dp psia

kav md

Q Cm3/m

501.3 1.4 877.5 5 500.2 2.8 877.6 10 503.3 4.1 898.9 15 503.3 5.4 910 20 494.8 1 1228.7 5 509.4 2.6 945.1 10 508.8 4.2 877.6 15 509.6 5.8 847.3 20 970.5 2.2 558.4 5 1000.5 4.8 511.9 10 1001 7.6 485 15

1016.7 11.3 434.9 20 1000.8 2.3 534 5 1002.2 5.8 423.6 10 1009.7 9.1 405 15 1002.7 13.9 353.6 20 1500.3 4.2 292.5 5 1504.6 9.3 268.2 10 1507.9 15.1 244.1 15 1504.8 21.4 229.6 20 1500.7 5 245.7 5 1506 10.9 225.4 10

1509.6 17.4 211.8 15 1509.6 22.5 218.4 20

Overburden experiments for unfractured core

Overburden experiments for fractured core

Experimental Results


0

200

400

600

800

1000

1200

1400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Overburden Pressure (Psia)

Per

mea

bili

ty (

md

)

Unfractured Core Fractured Core Expon. (Fractured Core) Expon. (Unfractured Core)

Permeability changes at variable overburden pressure

km

kav


Motivation

• How do we analyze the experimental results ?• What information can be deduced from experimental

results?• Fracture permeability• Fracture Aperture• Matrix and fracture flow contributions• How these properties change with overburden

stress• How do we model this experiment ?


Experimental Data Analysis

291045.8 wk f

wl

wlAkAkk mavf

)(

0)(1045.8 39 wlAkAklw mav

L

pAkq mm

L

plwq f 12

1086.93

9

wA

l

Parallel plate assumption:

Average Permeability :

Combine above equations to determine w:

Contribution flow from matrix and fracture systems:


0.00

50000.00

100000.00

150000.00

200000.00

250000.00

300000.00

0 200 400 600 800 1000 1200 1400 1600


Fra

ctu

re P

erm

ea

bil

ity

(m

d)

5 cc/min 10 cc/min 15 cc/min 20 cc/min

291045.8 wk f or wl

wlAkAkk mavf

)(

Fracture Permeability

: Hysteresis


0

0.001

0.002

0.003

0.004

0.005

0.006

0 200 400 600 800 1000 1200 1400 1600


Fra

ctu

re A

pe

rtu

re (

cm

)


Fracture Aperture

0)(1045.8 39 wlAkAklw mav

500 psia 1000 psia 1500 psia

w w w


0.00

5.00

10.00

15.00

20.00

25.00

0 200 400 600 800 1000 1200 1400 1600


Mat

rix

Flo

w R

ate

(cc/

min

)


Matrix Flow Rate

L

pAkq mm

Dual Porosity Dual Permeability Single Porosity


0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

0 200 400 600 800 1000 1200 1400 1600


Fra

ctu

re F

low

Rat

e (c

c/m

in)


Fracture Flow Rate

L

plwq f 12

1086.93

9

Km = 200 mdKf = 10,000-50,000 md

Dual Porosity Dual Permeability Single Porosity


Modeling Laboratory Experiment


Simulation Parameters

Single phase black oil simulation Laboratory dimensions (4.9875” x 2.51”) 31x1x31 layers Matrix porosity = 0.16764 Matrix permeability = 296 md Fracture properties is introduced in 16th layer Fracture porosity = 0.00563972 Mean fracture aperture = 56.4 micro meter Fracture aperture is varied using log normal

distribution and geostatistical approach Fracture permeability is generated from fracture

aperture distribution using modified parallel plate model


Example of flow through single fracture aperture


Simulation Results


0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

0 200 400 600 800 1000 1200 1400 1600


Flo

w R

ate

(c

c/m

in)

qf(Obs. Data) qf(Sim. Result) qm(Obs. Data) qm(Sim. Result)

Match between Laboratory data and Simulation Results


0

1

2

3

4

5

6

7

0 200 400 600 800 1000 1200 1400 1600


Pre

ss

ure

Dro

p (

Ps

ia)

dP(Obs. Data) dp(Sim. Result)

Match between Laboratory data and Simulation Results (Continued)


The fracture aperture (fracture permeability) must be distributed

Lesson Learned !


Actual Fracture Face


Log-normal Distribution of Fracture Aperture

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0 50 100 150 200 250 300 350

x( microM)

f(x

)


Generated Core Surface from Log Normal Distribution


Variogram Modeling to Generate Fracture Aperture Distribution


Core Surface Generated after Krigging


Example of flow through different fracture apertures


1. Change in overburden pressure significantly affects the reservoir properties.

2. The change in matrix permeability under variable overburden pressures is not significant in contrast with that effect on fracture aperture and fracture permeability.

3. The simulation results suggest that a parallel model is insufficient to predict fluid flow in the fracture system. Consequently, the spatial heterogeneity in the fracture aperture must be included in the modeling of fluid flow through fracture system.

Conclusions


5. The results also infer that the effect of stresses may be most pronounced in fractured reservoirs where large pressure changes can cause significant changes in fracture aperture and related changes in fractured permeability.

6. At high overburden pressure the influence of existing fracture permeability on fluid flow contributor in permeable rocks (> 200 md) is not too significant.

Conclusions (Cont’d)

Documents

Group PresentationOctober 2002 Fluid Flow Through The Fracture under Different Stress-state Condition Vivek Muralidharan Dicman Alfred Dr. Erwin Putra