GB1432975A - - Google Patents

Abstract

1432975 Seismic exploration AVANCE OIL & GAS CO Inc 9 April 1973 16896/73 Heading H4D A common reflection point seismic exploration method comprises producing seismic disturbances at each of a number of source points lying in respective different planes inclined to each other and each containing a respective seismic detector, and receiving at the detectors seismic reflections from a common subsurface reflection point which is in all the planes, the detectors being in an array having two dimensions in a generally horizontal plane. In the Fig. 3 plan view of an embodiment, source locations (S) are shown as squares, detector locations (D) as circles and reflection points (R) as dots. A "roll-along" survey method is used, points S being used in turn and all detector outputs being recorded for each actuation, whereby 8-fold coverage of points R along line B is afforded by intersecting ray paths 34, as well as 4-fold coverage of points R below line A or C. The use of inclined planes enables good recorded data to be selected for common depth point stacking, and rejection of poor data from, e.g. ray paths 24 interrupted by a geological fault. Alternative embodiments have the S and D points arranged in circular arrays (Fig. 1, not shown), or the D points on a set of parallel lines with the S points on alternate ones of the lines (Fig. 2, not shown).