Space-time-shift imaging condition and migration velocity analysis
时空移动成像条件及偏移速度分析

The imaging conditions of the depth-focusing velocity analysis and residual curvature velocity analysis are firstly compared.And then the time-shift offset domain common image gathers(TSODCIGs) and time-shift angle domain common image gathers(TSADCIGs) through the space-time-shift imaging condition are presented.According to the discussion on the TSADCIGs,the two criteria(depth-focusing criterion and flattening imaging gathers criterion) which were usually used by migration velocity analysis were unified together.Finally,based on the TSADCIGs,velocity update formulae were derived.A migration velocity analysis(MVA) workflow based on the time-shift common image gathers(TSCIG) was designed.This approach was numerically tested on synthetic and real seismic data.The numerical results demonstrated that the approach was feasible and effective for MVA.