A short-spread configuration for mapping dipping horizons in reflection seismic surveys

Summary In areas of steeply dipping seismic horizons, the conventional split-spread seismic reflection method may yield poor seismograms. In order to develop a suitable field technique to improve the record quality in such areas, an analysis of the effect of spherical divergence, reflection coefficient, and absorption on the amplitude of the signal reflected from a dipping interface has been carried out. It has been found that for a dipping interface the reflected signal amplitude in many cases may be higher for the larger angles of incidence at the reflecting bed than for the normal incidence. Thus, a suitable inline-offset spread in the updip direction is likely to increase the recorded reflected signal amplidute and improve the signal-to-noisre ratio in areas of dipping reflectors. The design of such a shot-spread configuration has been developed in this paper, and a field method using this configuration is suggested for continuous mapping of subsurface horizons.