Identification of Point Diffractor body placed in dipping Vertically Transverse Isotropic medium using Reverse Time Migration

Numerical modelling has been proved as an incomparable tool to understand the structure of the earth and the processes beneath the earth’s surface. Finite difference method (FDM) plays a dominant role among various numerical methods for the purpose of seismic modelling and exploration. FDM provides a comprehensible solution to the partial difference equations defining the propagations of seismic wave. These partial differential equations consist of derivatives in time and space domain. FDM can be applied by defining the elastic wave-field and model parameters at every position on a discrete mesh. Reverse-time migration (RTM) is based on exploding reflector model and it is better than other migration techniques for the interpretation of various seismic models. The present work shows the forward modelling and reverse time migration of point diffractor body placed in dipping layer of vertically transverse isotropic (VTI) medium. A 12^th order space and second order time differentiation RTM scheme have been used to interpret the location and extent of a point diffractor placed in dipping layer of VTI medium. The earth model under study is of the size 1400 m x 600 m. A dipping layer and a diffractor of size 18 m x 18 m has been placed in the VTI model. The FORTRAN code developed for FDM scheme of VTI model performs various requisite studies like stability criteria, numerical dispersion and the boundary conditions within the code. The output from the FDM code are the synthetic records at surface which after processing fed as an input in the FORTRAN code developed for RTM scheme. The position and extent of the diffractor placed in the dipping VTI medium layer has been detected properly using RTM scheme. Another FORTRAN code is developed in which forward and reverse wave propagation snapshots has been cross-correlated using various cross-correlation imaging conditions. A Laplace filter is then designed to efficiently resolve the position and extent of the diffractor in the dipping VTI medium layer.