Seismic modeling and inversion for reflections from fractures

Xiaoqin (Jean) Cui, Laurence R. Lines, Edward S. Krebes

We have studied a theory of linear slip nonwelded contact interfaces (Schoenberg, 1980) and extended the theory to simulate the subsurface fracture features by developing a 2D/3D numerical forward modeling method and a method of analysis of the PP and PS seismogram characteristics regarding the responses of the fractures (Cui, Lines and Krebes, 2012). In this paper we present a new AVO inversion equation that depends upon the theory of the linear slip nonwelded contact interfaces. We use the assumption that the two half spaces are in imperfect contact due to the presence of fractures, meaning that only the stresses produced by the wave are continuous across a fracture, and that the displacements are discontinuous across the fracture. The new equation can be inverted not only to estimate the subsurface elastic parameters contrasts, but also to estimate eight parameters related to the fractured media. This paper analyses fracture models and compares the results of numerical forward modeling between media with interfaces in perfect welded contact (no fractures) and with interfaces in imperfect linear slip nonwelded contact (with fractures). Inversion results of three models are also compared.