An approach for velocity determination from merging Archie and Raymer–Hunt–Gardner transform in reservoir of clean nature

Abstract

This paper introduces an empirical equation to approximately quantify the P-wave velocity especially in the absence of many logs and core usually used instantaneously to evaluate such parameter. Further, using the proposed equation with the help of Poisson's ratio, the S-wave velocity can be easily evaluated.The proposed equation is based mainly on merging the well-known Archie equation (1942) with the Raymer–Hunt–Gardner equation (1980). This equation takes into account the effects of both matrix and fluid transit times (Δtma, Δtf-with known type of lithology; sandstone, limestone and/or dolomite) as well as the formation water resistivity (RW), resistivity of fully saturated (R0), formation factor coefficients in terms of tortuosity factor (a), and cementation exponent (m). Further mathematical treatment for finding the VP/VS ratio from Anderson et al. (1973) of Poisson's ratio, the S-wave velocity could then be estimated.Comparison is made and agreement within an error not exceeding ±4 between predicted and actual values is reached. Successfulness of applying the proposed approach is restricted with the accuracy of finding RW and good selection of R0.Field examples from USA and the Gulf of Suez Basin of Egypt are illustrated to indicate the potentiality and validity of the suggested approach.