A Stereotomography Velocity Inversion Method in Imaging Domain

Generally, the data space needed for velocity inversion of stereotomographic is based on the slant stacking of local events on common shot point gathers and common detection point gathers in the data domain. This is a stable but inefficient data space pickup method suitable for 2 dimensional seismic data. Using pre-stack gathers for slant stacking is effective for primary wave in interactive picking, but the diffracted wave in complex structures can not be distinguished. Therefore, in view of the problem of inaccurate data space picking and large workload, this paper chooses a method of obtaining accurate stereotomography data space in the imaging domain under the condition of incorrect velocity. Firstly, extracting the common imaging point gathers by DSR (double square root equation) prestack depth migration method, which includes angle information of underground ray in migration process. Then residual curvature and local half-offset ray parameters are obtained. Then travel time residuals and corresponding ray parameters at shot point and receiving point are obtained. Then, real stereo is calculated by specific correction formula. Model tests shows that stereotomographic velocity inversion can improve the accuracy and stability obviously. This method will have better application in the practice of stereotomography inversion in the future.