COMPARISON OF INVERSION EFFICIENCY OF DIFFERENT AMPLITUDE VERSUS OFFSET (AVO) RELATIONSHIPS

Abstract

Amplitude-versus-Offset (AVO) inversion has been used to invert seismic reflection data to identify gas bearing sands. There are a number of relations which have been proposed to do this inversion. These relations have been derived from the basic Zoeppritz equations which are nonlinear. In order to be efficiently incorporated in reservoir modeling software, it is desirable that the inversion is linear in nature. Some simplifying assumptions are made in deriving these linear relations. These assumptions are not always satisfied in real earth. Synthetic seismic reflection data is first generated and then inverted using the different linear relationships. The efficiency of these relationships in obtaining model parameters will be determined and the effect of lithological changes on inversion efficiency will also be examined. The inversion efficiency of different inversion approximations will be considered on the basis of absolute error between the original model parameters and the inverted parameters. The process is conducted for the different basic types of gas sands i.e Class I, Class II, Class III and Class IV. The simulations on a synthetic 2-Layer model indicate that Shuey's approximation yields the lowest lowest absolute error in comparison to Zoeppritz Equations and Mallick's approximation yields the highest absolute error.