Porosity interpretation through seismics : Geoexploration V28, N1, April 1991, P91–106

Abstract

Abstract This paper describes a procedure for porosity interpretation from seismic data (POISE) by exploiting merits of several recent advances in seismic data processing and interpretation. Briefly, the procedure is as follows: starting from NMO corrected CDP gathers of P-wave data and applying amplitude versus offset (AVO) analysis, one can separate out zero offset “P-wave” and “Swave” stacks both as a function of P-wave time. Here the term “S-wave” refers to a stack that we would have obtained if we had carried out an S-wave survey and displayed the data in P-wave traveltime. Application of maximum likelihood deconvolution/modelling technique on stacks leads to models for P-wave and S-wave reflection coefficients. Finally, inverting the reflection coefficients for interval transit time, a section can be prepared to display ΔT s - ΔT p , the difference in slowness of the S-wave and P-wave as a function of the P-wave traveltime. The final output of POISE for ΔT s - ΔT p is particularly useful for studying variations in lithology and porosity within a formation. The interpretation is fouSnded on an empirical observation by Ikwuakor that ΔT s - ΔT p from character logs for a large number of carbonate and sandstone samples, is proportional to the core porosity (for a given rock type). The utility of POISE is illustrated with a field example in a carbonate reservoir.