Geomechanical Brittleness Estimation Through Simultaneous Pre-stack Inversion

Abstract

Information about mechanical rock properties is an essential understanding when tight reservoir such as in the tight sand plays or oil/gas shale plays will be stimulated using hydro-fracturing technique. Not only for stimulation reservoir, but also the information of brittleness of shale formation also is needed when seal or cap rock of formation is evaluated. The elastic moduli of rock that can be correlated with geomechanical process such as the brittleness, Poisson’s ratio, and Young’s modulus can be derived from seismic data. In this study, we derived the brittleness, Poisson’s ratio, and Young’s modulus from seismic data using simultaneous pre-stack inversion. The data used in this work are from Malay basin field. The data consist of well data and seismic data (near stack 5°–15°, mid-stack 15°–25°, and far stack 25°–40°). The data were analyzed and processed to get the compressional velocity, shear velocity, and density volume through simultaneous pre-stack inversion. Poisson’s ratio, Young’s modulus, and brittleness are calculated afterward. The results show that the compressional wave velocity, shear wave velocity, and density resulted from simultaneous pre-stack inversion are consistent with well log. The shale formation above main reservoir has high Poisson’s ratio, high Young’s modulus, and low brittleness index.