Pacific Section AAPG, SPE and SEPM Joint Technical Conference

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Results Of The Core/Log Comparison In Kern River Well

Abstract

In December of 2012, over 800 ft of whole core was captured from a temperature observation well in Kern River. In addition, several logs were run including: PeX-ADT, ECS, LithoScanner, FMI, and RST. Routine core analysis, including porosity, permeability, and saturation measurements, was conducted on over 600 plugs. These samples span the productive range of the Kern River Formation and include steam chests, oil-saturated sands, and water-saturated sands. The goals of this effort were to verify the nature of the sand /silt contacts, estimate the accuracy of saturation estimates from logs, and identify opportunities for improving our understanding of current oil in place. To this end, we noted in the core photos sharp contacts between sands and siltstones. We also took samples for total organic carbon (TOC) measurements that definitively demonstrate the absence of oil in Kern River siltstones. The saturation results from the 600+ core plugs were compared against the saturations from PeX-ADT and RST. The results showed < 2 su difference, on average, in the results from all three sources. We also used porosity and saturation results from the core along with temperature, porosity, and RST logs to examine methods of improving the accuracy of our estimates. These include using TOC from LithoScanner to calibrate RST response and correcting our resistivity and porosity logs using post-casing temperatures. In addition to routine core analysis, we also collected CEC, mineralogy, and rock chemistry data in ∼40 core plugs. We compared TOC from core to TOC reported by the LithoScanner, and we compared oil saturation derived using the 2 estimates of TOC. We also compared CEC measurements from core to log-derived CEC estimates from the Dielectric Scanner (ADT). Finally, we compared rock chemistry and mineralogy from core to LithoScanner and ECS. Results varied, but, in general, each technology showed promise, and best practices and lessons learned were obtained from each comparison.