qP wave forward modeling in fracture media with monoclinic symmetry
Qin Haixu1,2, Wu Guochen3, Liu Zhengping1
1. School of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China;
2. The Third Railway Survey and Design Institute Group Corporation, Tianjin 300251, China;
3. School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China
Abstract：Wave forward modeling in fracture media has significance for understanding the nature of fracture media and predicting fractural reservoirs. We use monoclinic model, the simplest model, to describe realistic fractured reservoirs in monoclinic fracture systems in the purely isotropic layer. First, a fracture medium is equivalent to the monoclinic anisotropic medium according to the equivalent theory, which establishes the relationship between fracture parameters and elastic parameters. Second, a qP wave equation is established according the dispersion relation, and this equation can avoid the complexity of the elastic wavefield and the coupling of P wave and S wave. Last, the wavefield of qP wave in two groups of vertical and oblique fractures is simulated according to the finite difference numerical simulation. The result shows that the wave front of qP wave is neither circle nor ellipse, and that different azimuthal seismic records have some difference in travel time and amplitude. This work has significance for understanding wavefield in vertical and oblique fracture media.
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