Optimization of Behind Casing Resistivity Analysis Using Nuclear Logs

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractConventional resistivity analysis has been used for evaluation of hydrocarbon saturation in both exploratory and development wells. Resistivity logs are however not sufficient for performance of a fluid characterization because resistivity cannot detect variation in hydrocarbon densities. As a result, additional logs such as nuclear, sonic and nuclear magnetic resonance logs are required to perform a satisfactory evaluation of hydrocarbon fluid typing and saturation computation. This paper focuses on recommended best practices for combination of behind casing resistivity measurements and complementary logs in matured fields for evaluation of hydrocarbon/water contacts, detection of by-passed reserves and fluid typing.An example from the eastern Niger Delta shows where cased hole formation resistivity results were optimized with pulsed neutron spectroscopy measurements in performing a successful workover program and improving production rates by over 80%