Improving the accuracy of seismic prediction of the effective thicknesses of the Ju2 formation of the Tyumen suite on the example of the fields of the Tortasinsky block

UDK: УДК 550.34.06.013.3

DOI: DOI: 10.24887/0028-2448-2021-11-28-31

Key words: facies depositional environment, seismic attribute, simultaneous inversion, spectral decomposition

Authors: E.F. Gaifulina1, N.V. Nadezhnitsskaya1, Yu.S. Kapustina1, S.D. Dariy2, E.V. Meleshkevich3, R.S. Melnikov3 1Tyumen Petroleum Research Center, RF, Tyumen 2Sorovskneft LLC, RF Tyumen 3Rosneft Oil Company, RF, Moscow

The main purpose of geologists and geophysicists work is creation of a reliable consistent geological model of a target area. At the same time, one of the main problems is the reliability of seismic predictions of reservoir parameters in complex reservoirs. The article discusses the features of predicting effective thicknesses from seismic data for the deposits of the Ju₂ formation of the Tyumen suite in case of the group of fields in the Tortasinsky block. The upper part of Tyumen suite is productive almost for all deposits of Khanty-Mansiysk Autonomous District. Deposits of Ju₂ strata were formed in transitional depositional environment of a coastal plain. Distinguishing features of Middle Jurassic deposits are: laterally poorly continuous shale barriers, high heterogeneity, low thickness of sandy-silty layers (close to seismic resolution), laterally abrupt sandstone facies replacement with mudstone and siltstone, presence of carbon-bearing interlayers - all of these form a complex structure of a predicted interval. Therefore, facies analysis is one of the most important tools for oil and gas reservoir study. The use of multi-scale geological and geophysical information including 3D seismic data enable interpreters to perform lateral wave pattern variation analysis and based on it identify the main facies, specified their internal structure and formation features.

Based on results obtained by specialists of Tyumen Petroleum Research Center, Sorovskneft and Rosneft it is shown that dividing of a study area into facies zones gives opportunity to improve prediction accuracy of effective thickness based on seismic attributes. The outcome of this work allow to specify hydrocarbon prospects of Ju₂ strata deposits of Tyumen suite in Tortasinsky license areas of Rosneft Oil Company. 

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