PSEUDOREFLECTION PROFILING METHOD: AN EFFICIENT COMPLEMENT TO CDP METHOD1

A method for pseudoreflection profiling (PRP) is presented. By using transmission seismograms, this method produces time sections similar to those obtained using the common depth point (CDP) method. Pseudoreflection profiles are obtained using the following procedure. Equivalent transmission responses at sites on soft deposits are derived by Wiener filter estimation using seismograms acquired on the sites and on the basement rock. These responses are substituted into the Claerbout-Kunetz equation to obtain the pseudoreflection profiles. A 3D subsurface model is produced when the PRP method is applied to explosion seismograms. The time sections thus obtained are consistent with those obtained using the CDP method in a neighbouring area. The maximum station interval for obtaining coherent profiles with this method is estimated to be one quarter of the wavelength of the transmitted waves. This technique should be used in combination with another method such as the CDP method because it has two weak points: the velocity structure cannot be obtained directly and undesirable waves cannot be eliminated through processing.