QUANTITATIVE CALCULATION OF ACQUISITION FOOTPRINTS FOR 3D LAND SEISMIC ACQUISITION GEOMETRIES

摘要

An inappropriate acquisition geometry can leave a strong footprint on the stack of 3D seismic data, which would reduce the accuracy of seismic processing and interpretation. However, it is difficult to completely eliminate acquisition footprints using processing methods. In this paper, we propose a quantitative method to calculate the acquisition footprints for given 3D land seismic acquisition geometries, which improves on the usually qualitative methods used in classical seismic geometry design. Our method can obtain the acquisition footprints at any target depth based on the seismic wave propagation (WRW) model in terms of matrix operators in the frequency domain. The footprint is expressed as. relative amplitudes of a stacked image of primaries for every source-receiver pair. With the proposed approach, we could quantitatively evaluate the acquisition footprints of different seismic acquisition schemes for any target depth and ultimately choose the optimal acquisition parameters that would yield the minimal possible footprint before initiating fieldwork. Through two theoretical examples, we investigate the influence two key acquisition parameters, the shot traverse spacing DS and the number of receiver lines repeated in a crossline roll-along K, have on acquisition footprints. Herein, a case study in an oilfield in China is presented by computing the footprint at different depths for different acquisition geometries. The results show that the qualities of the seismic migrations can be greatly improved by choosing the optimal geometry, which has the smallest possible acquisition footprint.