Micro-seismic forward modeling in visco-elastic TTI media based on rotated staggered grid finite-difference method

Abstract

Based on visco-elastic anisotropic first-order velocity-stress wave equations presented by Carcione, micro-seismic wave fields, records, and illumination maps are acquired by the rotated staggered grid finite-difference forward modeling. With seismic moment tensor decomposition, the force source is turned into velocity source and then loaded on the rotated staggered grids for ISO, DC and CLVD three kinds of basis sources. Micro-seismic wave field characteristics are analyzed at the same time and the following observation are obtained: (1) The relative strength between qP-wave and qSV-wave, and the qP-wave first-motion focal mechanism solutions are only restricted to focal mechanism; this can be used to investigate different focal mechanism and inverse fracture parameters. (2) qP-wave arrival time is only subjected to reservoir property, so qP-wave event curvature can be set as prior information for reservoir prediction. (3) Both focal mechanisms and medium types will affect the micro-seismic event radiation pattern and there are many differences among different cases. So different prior information should be considered for energy orientation optimization in the geometry design process.