Determination of Some Geo-Mechanical Parameters and the Effect of Anisotropy in Sedimentary Rocks for Hydrocarbon Exploration and Exploitation Using Core Samples in Western Part of Tripura, India

Abstract

The velocity anisotropy parameters and elastic constants play very important role to estimate Youngs modulus and Poissons ratio accurately. For geomechanics applications such as hydraulic fracturing design, analysis of wellbore stability and rock failure, determination of in situ stress and assessment of the response of reservoirs and surrounding rocks to changes in pore pressure and stress, Youngs modulus and Poissons ratio play very important role.

Four rock samples were collected from four different wells situated in study area. The ultrasonic transmission method has been used to measure P wave, Sh wave and Sv wave travel times as a function of orientation and confining pressure. The five independent stiffnesses constants, Youngs moduli, Poissons ratio and Bulk moduli of the samples were estimated.

The Poissons ratios  are varying as the confining pressure is changed. The axial strain is larger than the lateral strain, resulting . For shales, the Youngs modulus measured parallel to bedding E₁ is usually greater than the Youngs modulus measured perpendicular to bedding E₃. Through this study it has been observed that there is a strong effect of anisotropy parameters on Youngs modulus and Poissons ratio.