Calculations of rock matrix modulus based on a linear regression relation
He Xi-Lei1, He Zhen-Hua1, Wang Rui-Liang2, Wang Xu-Ben1, and Jiang Lian1
1. State key laboratory of oil and gas reservoir geology and exploitation, Chengdu University of Technology, Chengdu 610059, China.
2. CNOOC Shenzhen Inc. Shenzhen 518067, China.
Abstract：
The rock matrix bulk modulus or its inverse, the compressive coefficient, is an important input parameter for fluid substitution by the Biot-Gassmann equation in reservoir prediction. However, it is not easy to accurately estimate the bulk modulus by using conventional methods. In this paper, we present a new linear regression equation for calculating the parameter. In order to get this equation, we fi rst derive a simplifi ed Gassmann equation by using a reasonable assumption in which the compressive coefficient of the saturated pore fl uid is much greater than the rock matrix, and, second, we use the Eshelby-Walsh relation to replace the equivalent modulus of a dry rock in the Gassmann equation. Results from the rock physics analysis of rock sample from a carbonate area show that rock matrix compressive coeffi cients calculated with water-saturated and dry rock samples using the linear regression method are very close (their error is less than 1%). This means the new method is accurate and reliable.
HE Xi-Lei,HE Zhen-Hua,WANG Rui-Liang et al. Calculations of rock matrix modulus based on a linear regression relation[J]. APPLIED GEOPHYSICS, 2011, 8(3): 155-162.
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2011, Vol. 8 
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