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Majalah Ilmiah UNIKOM

Vol.6, No. 2

186

H a l a m a n

The existence of fluid in fracture will raise

stiffness value of medium significantly, it is

caused by increasing compressibility K

f

.

NUMERICAL STUDY OF FLUID INCLUSION

EFFECT IN FRACTURE TO THE AVO

PARAMETER

Using MATLAB 6.5.1 we studied AVO

(amplitude various offset) parameter

change to the fluid change of fluid content

of fracture. This experiment is to design

the best AVO parameter that most

sensitive to detect fluid content in fracture.

We use following data to model the AVO :

Physical data of upper Medium

Density

:1000 kg/m

3

a

: 900 m/s

b

: 500 m/s

Physical data of Lower Medium

Density

: 1473.9 kg/m

3

a

: 1842.10 m/s

b

: 1195.47 m/s

Anisotropy Degree

VTI :

HTI :

d : 0.1, e : 0,06 dan g : 0.08

Bulk Modulus of Fluids : 2.2 GPa (water)

Bulk Modulus of Material : 40 GPa

Porosity : 0,27

Figure 1, show the result of the modeling.

CONCLUSIONS

It is shown in figure 1 that we can model

the AVO response using MATLAB 6.5.1 as

numerical computation. According to the

result, we see that AVO respon is increase

with incident angle due to fluid inclusion

GPa

.

5

)

10

.

1842

)(

9

.

1473

(

C

2

2

o

33

GPa

9

.

1

)

29

.

1163

)(

9

.

1473

(

C

2

2

o

55

GPa

6

.

5

)

748

.

1941

)(

9

.

1473

(

C

2

2

o

11

GPa

2

.

2

)

21

.

1226

)(

9

.

1473

(

C

2

2

o

66

about 30 %. The increase is caused by

bulk modulus of the pore fluid.

REFERENCES

Thomsen, L. (1992). Seismic And Acous-

ticVelocities in Reservoir Rocks Volume

Geophysics Reprint

Series

Geophysicist

Pore Fluid

Effects on Seismic Anisotropy

ford Rock Physics and Borehole Project

Understanding Seis-

mic Anisotropy in Exploration an Exploi-

tation

scientist & engineers.

Brown R.J.S. & Korringa, J. (1975) On De-

pendence Of Elastic Properties Of a

Porous Rock on the Compressibility of

Geophysics

616

Fluid Substitution

Theories and Multicompnent Seismic

Characterization of Fractured Reser-

voir

Phenomena Colorado School of Mines.

Numeri-

cal Methods Using MATLAB

wood.

Ishaq, U.M. & Nurhandoko, E.B.

(December 2005).

Study of seismic

wave in fractured reservoir rock using

Empty pores

Water

Figure1

AVO Modeling Using MATLAB 6.5.1

USEP MOHAMAD ISHAQ