TITLE:
Estimation of the Effect of Anisotropy on Young’s Moduli and Poisson’s Ratios of Sedimentary Rocks Using Core Samples in Western and Central Part of Tripura, India
AUTHORS:
Jwngsar Brahma, Anirbid Sircar
KEYWORDS:
Elastic Stiffness; Shales; Sandstone; Sedimentary Rock; Anisotropy
JOURNAL NAME:
International Journal of Geosciences,
Vol.5 No.2,
February
26,
2014
ABSTRACT:
The velocity anisotropy parameters and elastic constants play a very important role to estimate
Young’s modulus and Poisson’s ratios 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, Young’s modulus and Poisson’s ratios play a 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,
Young’s moduli, Poisson’s ratios and Bulk moduli of the samples were estimated.
The Poisson’s ratios ( and ) are
varying as the confining pressure is changed. The axial strain is larger than
the lateral strain, resulting . For
shales, the Young’s modulus measured parallel to bedding E1 is
usually greater than the Young’s modulus measured perpendicular to bedding E3.
Through this study it has been observed that, there is a strong effect of
anisotropy parameters on Young’s modulus and Poisson’s ratio.