三维共偏移距叠前地震数据反假频射线束形成偏移成像

We propose triangle filter anti-aliasing beam forming to attenuate the migration operator aliasing for the three dimensional beam migration on the real sparse acquisition marine seismic data. Slant stack is an effective way for beam forming, which picks up the local linear seismic events in the seismic profile. The ray parameters in the slant stack is an approximate of the migration operator dip and anti-aliasing is a low-pass frequency filtering operation according to the sampling theory. The frequency band of the filter is determined by the ray parameters of the migration operator dip. Time domain slant stack is the summation of the time shifted seismic traces. The triangle filtering can also be conducted in the time domain. It is also summation of the time shifted data after casual and anti-causal integral. Therefore, triangle filtering and slant stack can be incorporated in the time domain which avoids the transform of data from time to frequency domain. We propose to add weighting factors in the anti-aliasing formula to control the trade off between noise suppression and the resolution decreasing of the steep structures in the image. The three dimension stack image and the common image point offset gathers from the real seismic data show that the proposed method suppresses the operator aliasing effectively.