Abstract: Method for constructing an integrated rock physics model that simulates both shale anisotropy and stress-induced anisotropy of clastic rocks. In the model, the total pore volume is divided into three parts according to the estimated shale volume and effective stress: (1) clay-related pores, (2) sand-related pores, and (3) microcracks (mainly in the sand component). The pore space is then partitioned into the clay-related and sand-related pores using a scheme first disclosed by Xu and White in 1995. The model simulates shale anisotropy via the preferred orientation of clay-related pores and stress-induced anisotropy via the preferred orientation of microcracks, which is controlled by the differential stresses. Laboratory measurements or well logs are needed to establish a relationship between crack density and the effective stress.

Abstract: Method for predicting lithology and porosity of subsurface rocks from seismic reflection data. The seismic data is inverted to yield elastic properties of the rocks such as the compressional and shear impedances. A rock physics model is built to relate porosity, the shale volume fraction, the fluid content of the rock and the elastic properties of the rock. The model is run backward in a second inversion process to solve for porosity and lithologic properties such as the shale volume fraction.