Известия Томского политехнического университета: Инжиниринг георесурсов (Jun 2019)
INTENSITIES OF SUPERIMPOSED EPIGENESIS AS INDICATORS OF OIL SATURATION IN SANDSTONE RESERVOIRS
Abstract
The relevance of the research is caused by the possibility to identify missed (low-resistivity) productive reservoirs in sandstone intervals, based on the available well-logging data with the focus on the intervals with no core data. The aim of the research is to apply the intensity of superimposed epigenetic processes in sandstones as an indicator of oil saturation in sandstone reservoirs in Western Siberia. Objects: Upper Middle Jurassic sandstone deposits in Tomsk region and Achimov sequence of early Cretaceous sandstone deposits in Samotlor field. Methods. A proprietary innovative statistical technique to interpret well-logging data is used to identify the intensities of superimposed epigenesist of kaolinitization, carbonatization, pyritization, pelitization and missed low-resistivity hydrocarbon-bearing reservoirs. Results. It is proved that the intensity parameters of superimposed epigenesis of kaolinitization and pyritization for Jurassic and Cretaceous sand deposits in Western Siberia can be used as indicators of oil saturation in the reservoirs. The cutoff values for Tomsk region and Samotlor are identified. Paragenesis of superimposed epigenetic processes of pyritization and kaolinitization in sandstone intervals signifies hydrocarborn saturation of the intervals. Empirical evidence proves that the success rate of the applied indicators is ~75–80 % if the indicators are estimated by the innovative statistical technique for well logging data interpretation. Conclusion. The use of the innovative statistical technique for well logging data interpretation allows identifying missed oil-bearing low-resistivity intervals based on the well-logging data obtained earlier. It also enables solving lithological, petrophysical, and geological tasks (conditioned by deep fluid migration) while oil and gas prospects.
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