IJG  Vol.5 No.2 , February 2014
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
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.


Cite this paper
Brahma, J. and Sircar, A. (2014) 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. International Journal of Geosciences, 5, 184-195. doi: 10.4236/ijg.2014.52020.
References
[1]   L. Thomsen, “Weak Elastic Anisotropy,” Geophysics, Vol. 51, No. 10, 1986, pp. 1954-1966.
http://dx.doi.org/10.1190/1.1442051

[2]   T. Alkhalifah and I. Tsvankin, “Velocity Analysis for Transversely Isotropic Media,” Geophysics, Vol. 60, No. 5, 1995, pp. 1550-1566.
http://dx.doi.org/10.1190/1.1443888

[3]   N. C. Banik, “Velocity Anisotropy of Shales and Depth Estimation in the North Sea Basin,” Geophysics, Vol. 49, No. 9, 1984, pp. 1411-1419.
http://dx.doi.org/10.1190/1.1441770

[4]   D. F. Winterstein, “Velocity Anisotropy Terminology for Geophysicists,” Geophysics, Vol. 55, No. 8, 1990, pp. 1070-1088. http://dx.doi.org/10.1190/1.1442919

[5]   R. Brown and J. Korrigan, “On the Dependence of the Elastic Properties of a Porous Rock on the Compressibility of the Pore Fluid,” Geophysics, Vol. 40, No. 4, 1975, pp. 608-616. http://dx.doi.org/10.1190/1.1440551

[6]   J. A. Hudson, “Overall Properties of a Cracked Solid,” Mathematical Proceedings of the Cambridge Philosophical Society, Vol. 88, No. 2, 1980, pp. 371-384.
http://dx.doi.org/10.1017/S0305004100057674

[7]   J. A. Hudson, “Wave Speeds and Attenuation of Elastic Waves in Material Containing Cracks,” Geophysical Journal International, Vol. 64, No. 1, 1981, pp. 133-150.
http://dx.doi.org/10.1111/j.1365-246X.1981.tb02662.x

[8]   J. A. Hudson, “Overall Elastic Properties of Isotropic Materials with Arbitrary Distribution of Circular Cracks,” Geophysical Journal International, Vol. 102, No. 2, 1990, pp. 465-469.
http://dx.doi.org/10.1111/j.1365-246X.1990.tb04478.x

[9]   J. A. Hudson, “Crack Distribution Which Accounts for a Given Seismic Anisotropy,” Geophysical Journal International, Vol. 104, No. 3, 1991, pp. 517-521.
http://dx.doi.org/10.1111/j.1365-246X.1991.tb05698.x

[10]   J. A. Hudson, E. Liu and Crampin, “The Mechanical Properties of Materials Which Interjected Cracks and Pores,” Geophysical Journal International, Vol. 124, No. 1, 1996, pp. 105-112.
http://dx.doi.org/10.1111/j.1365-246X.1996.tb06355.x

[11]   T. Mukerji and G. Mavo, “Pore Fluid Effects on Seismic Velocity in Anisotropic Rocks,” Geophysics, Vol. 59, No. 2, 1994, pp. 233-244.
http://dx.doi.org/10.1190/1.1443585

[12]   L. Thomsen, “Elastic Anisotropy Due to Aligned Cracks in Porous Rock,” Geophysical Prospecting, Vol. 43, No. 6, 1995, pp. 805-829.
http://dx.doi.org/10.1111/j.1365-2478.1995.tb00282.x

[13]   T. D. Jones, “Wave Propagation in Porous Rock and Models for Crustal Structures,” Ph.D. Thesis, Standford University, 1983.

[14]   N. M. Lucet and P. A. Tarif, “Shear—Wave Birefringence and Ultrasonic Shear Wave Attenuation Measurements,” SEG Annual Meeting, Anaheim, 30 October-3 November 1988, pp. 922-924.

[15]   M. Zamora and J. P. Porier, “Experimental Study of Acoustic Anisotropy and Birefringence in Dry and Saturated Fontainebleau Sandstone,” Geophysics, Vol. 55, No. 11, 1990, p. 1455. http://dx.doi.org/10.1190/1.1442793

[16]   B. E. Hornby, “Experimental Laboratory Determination of the Dynamic Elastic Properties of Wet, Drained Shales,” Journal of Geophysical Research: Solid Earth, Vol. 103, No. B12, 1998, pp. 29945-29964.

[17]   Z. Wang, “Seismic Anisotropy in Sedimentary Rocks,” Part 1: A Single-Plug Laboratory Method,” Geophysics, Vol. 67, No. 5, 2002, pp. 1415-1422.
http://dx.doi.org/10.1190/1.1512787

[18]   K. Bjørlykke, “Clay Mineral Diagenesis in Sedimentary Basins—A Key to the Prediction of Rock Properties. Examples from the North Sea Basin,” Clay Minerals, Vol. 33, 1998, pp. 15-34.

[19]   M. S. Sam and A. Andrea, “The Effect of Clay Distribution on the Elastic Properties of Sandstones,” Geophysical Prospecting, Vol. 49, No. 1, 2001, pp. 128-150.
http://dx.doi.org/10.1046/j.1365-2478.2001.00230.x

[20]   Z. Wang, “Seismic Anisotropy in Sedimentary Rocks, Part 2: Laboratory Data,” Geophysics, Vol. 67, No. 5, 2002, pp. 1423-1440.
http://dx.doi.org/10.1190/1.1512743

[21]   J. M. Leslie and D. C. Lawton, “A Refraction Seismic Field Study to Determine the Anisotropic Parameters of Shales,” The Leading Edge, Vol. 17, No. 8, 1998, pp. 1127-1129. http://dx.doi.org/10.1190/1.1438105

[22]   G. Mavko, T. Mukerji and J. Dvorkin, “Rock Physics Handbook: Tools for Seismic Analysis in Porous Media,” Cambridge University Press, 1998.

[23]   F. R. Pena, “Elastic Properties of Sedimentary Anisotropic Rocks,” Dissertation, Massachusetts Institute of Technology, 1998, pp. 19-26.

 
 
Top