Improved Rock-Physics Model for Shale Gas Reservoirs

Abstract

Unconventional resources such as shale gas are becoming increasingly important exploration, development, and production targets. However, geophysical characterization of these unconventional reservoirs remains challenging because of limited understanding of geophysical responses to reservoir properties such as total organic carbon (TOC). We have developed an improved anisotropic rock-physics model to incorporate TOC effects, in addition to effects of mineralogy, porosity, and fluid content, on seismic and electrical properties of shale gas. The modeling results suggest that an increase in the organic content generally reduces P-impedance, and Vp/Vs ratio, while increasing the velocity anisotropy and resistivity. This general trend is further modified by mineralogical compositions.