An improved rotated staggered grid finite difference scheme in coal seam

Coal seam is thin compared to the wavelength of seismic wave and usually shows strong anisotropy. It may form special geological bodies such as goaf and collapse in coal mining. The existence of these phenomena may lead to instability in numerical simulation of goaf area in coal seam. And the calculation speed of simulation is always a factor that restricting the development of simulation technique. To improve the accuracy and efficiency of seismic numerical simulation of goaf area, an improved vacuum method has been imported in a rotated staggered grid scheme and the calculation is implemented by combining parallel computing and task parallelism. It makes sure that the numerical simulation method can be utilized in a geological model with large differences in elastic parameters among layers and improve the performance of a parallel application by enabling full use of processor resources to expedite calculation speed. We set up anisotropic coal seam models, and then analyze the characteristics of synthetic seismograms and snapshots of different goaf areas with or without collapse by modeling. Results show that the proposed method can accurately simulate the goaf area and the calculation method can run with high speedup ration and parallel efficiency. The research will further advance the technology of anisotropic seismic exploration in coal fields, provide data for seismic inversion and give a theoretical support for coal mine disaster prediction.