Abstract:The conventional design of seismic geometry is on the basis of hypotheses of underground horizontal layered medium and common-mid-point(CMP)coverage,which is not suitable for the complex structural situations.The analytic approach of ray-based seismic wave illumination has shortcomings of high-frequency approximation and ray theory itself,and has lower precision in the area of complex targets.Starting from wave equation forward simulation,the paper presented the design method of target-oriented seismic geometry,which is based on geologic-geophysical model,using staggering grid high-order finite-difference algorithm of two-way acoustic wave equation to compute the illumination of seismic waves.Faced with complex fault block model in Jizhong area,the paper carried out optimum design of target-oriented seismic geometry,discussed with the emphasis on the influence of geophone interval on imaging quality and got the following knowledge:①there is one-to-one relationship between the imaging quality of local target and the strength of illumination on the target since the complex fault-block structure caused non-uniform distribution of propagation energy of seismic waves;②the strength variation of two-way illumination is distinctive for same source and different receiver interval at the same time,from which the optimum target-oriented receiver interval can be determined;③for the CRP on same incline interface,the variation raw of strength of two-way illumination at different shot points with different CRP in incline direction is different,the energy distribution received from horizontal target and incline target illuminated by source is different on surface,but the strength of energy and imaging result of migration are consistent,from which the optimum distributing range of shot and receiver points can be determined;④the variation of group interval and spread length have clear influence on the imaging amplitude and resolution of seismic waves;using point-expansion function(or resolution function)can evaluate the seismic imaging quality and resolution,and also can determine such acquisition parameters as the optimum receiver interval and spread length.The practice showed that the method in the paper is feasible for optimized target-oriented design of seismic geometry.