Exploration system for cross-steering and stacking seismic data using a sawtooth traverse of shot points centrally spaced between at least a pair of linear detector spreads

Claim 1

A seismic exploration method where seismic impulses are generated successively, one pulse at each of a plurality of source point locations along an asymmetrical sawtooth shot point line, having a stepped segment defining an offset spacing distance (d), between adjacent source point locations, and where seismic waves resulting from each of said impulses are detected by at least two detector spreads each containing a plurality of detectors spaced at a series of in-line detector locations, adjacent spreads being offset from each other a distance D, which is related to said source point spacing distance (d) by a ratio of 2:1 or greater which comprises: i. statically and dynamically correcting detected seismic signals so as to produce a series of corrected traces, said series of corrected traces containing sets of common traces associated with common centerpoints of a two-dimensional grid of centerpoints formed between particular source point location and detector spread location pairs, and cross-sets of traces associated with cross-lines of centerpoints of said grid, at least one trace of each set of common centerpoint traces being a product of a source-detector pair having a substantially different horizontal spacing than at least one other source detector pair of other common traces associated with said same set of common centerpoint traces, ii. stacking said sets of common traces to produce stacked traces having improved primary-to-multiple ratios which improve the portrayal of multifold areal surface structural conditions, and iii. beam-steering said stacked traces to produce subsets of cross-directional traces having improved directional content and signal-to-noise ratios.