The Study On The Relationship Of The Offset Uniformity And Pre-stack Time Migration Response

Seismic data acquisition is essential to seismic exploration because the quality ofacquired data determines the accuracy of seismic data processing. For better migratingthe data, Vermeer proposed a balanced acquisition method, which guarantees theuniformity of acquisition spacing. Balanced sampling guarantees the observationsystem can simultaneously obtain shallow、medium and deep reflection information ofthe target layer, making maximum use of seismic data migration. However, the levelof balance of acquisition can only be qualitatively and empirically estimated. Soproposing more accurate and quantitative estimation method is a very imperativeproblem for seismic data acquisition. In this paper, we has introduced uniformity ofshot-receiver distance to describe the level of balanced acquisition of the entireobserving system, and discussed the effects of the sampling uniformity on migration。This paper contains four parts:1) introduction of uniformity of shot-receiverdistance and its analysis method;2) discussion of effects of offset uniformity onvelocity analysis and migration;3) discussion of effects of Offset uniformity onPre-stack time migration for earth observation system;4) discussion of effects ofOffset uniformity on Pre-stack time migration for marine observation system. In theresearch, it shows that the offset uniformity determines the quality of velocity analysisand migration imaging very well; the sensitivity of structures in different depth to thisuniformity varies with different position, so does the contribution of gathers indifferent traces to migration; The increasing of receive/OBS spacing will combinedinfluence the quality of velocity analysis and migration imaging from decreasingseismic data information (decreasing offset uniformity), reducing the accuracy ofvelocity field, spatial aliasing several aspects. This conclusion is very useful such asguiding seismic geometry design.