Integration of a Multi-Frequency Dielectric Measurement and Advanced Wireline Logs for the Enhanced Characterization of Carbonate Reservoirs of the Western Kazakhstan

Abstract

Saturation evaluation based on resistivity methods have been widely accepted industry standard for the decades. Formation Evaluation in carbonates usually relatively straightforward due to simple lithology and resistivity-based methods works perfectly due to high formation water salinity. However, complexity and variation of carbonate texture and wettability makes estimating of saturation solely on resistivity methods challenging especially in case of the paucity of special core analysis (SCAL) data. New developments in logging technology, especially in dielectric logging, is aiming to improve the log derived interpretation and reduce the uncertainties of the evaluation. Outputs of dielectric dispersion logs including computation of Archie's parameters (m=n), water-filled porosity enable clearly identified the hydrocarbon-bearing zones despite misleading oil saturation calculated using resistivity-dependent saturation approach in front of most porous reservoir. Water saturation computed with inverted from dielectric measurement Archie's parameters allows accurately identify the type of fluid (hydrocarbon or water) filling the free pore space and gain insight prior to the formation sampling and well test. The objective of this work is to describe a comprehensive approach integrating dielectric measurement and other advanced sets of wireline logs for petrophysical characterization of carbonate reservoirs. This paper is intended to discuss in detail a case study from the Western Kazakhstan in which the integration of advanced petrophysical logs has enabled a robust reservoir and fluid characterization of carbonate reservoir and provided insights for formation testing results in advance. The extensive logging suite to address all the key challenges included standard logging, dielectric dispersion, nuclear magnetic resonance, and formation microimager. The reservoir fluids and dynamic properties were characterized by a series of formation sampling. The integration of dielectric, nuclear magnetic resonance and formation microimager measurements has played a major role in characterizing formation heterogeneity and reveal pore structure type, a dielectric multi-frequency measurement is being utilized to measure the flushed zone oil saturation relatively independent of pore fluid salinity, rock texture, and composition. The comparative analysis of well-logging and well-test results was carried out. Saturation types of 6 tested objects out of 6 obtained from well-test show perfect match with predicted reservoir saturation from petrophysical evaluation.