The article is devoted to a problem of improving a reliability of detailed seismogeological models of hydrocarbon deposits at the assets of Rosneft Oil Company. The problem of predicting lithology between wells in three-dimensional geological models especially emerges in areas with a complex geological structure. Standard seismic interpretation tools are limited by a vertical seismic resolution which is an insufficient for geological modeling. In such situation stochastic seismic inversion can help to reduce a degree of uncertainty in predicting a lithological structure of oil and gas reservoirs. Stochastic seismic inversion is a process of building a volumetric reservoir model with a distribution of properties described by wells and calculated wave field based on them which is similar to real seismic data. At the same time, the built geological model has the same vertical resolution as log data. A distinguishing characteristic of the method is its multivariance: a result of stochastic inversion has a set of equally probable realizations of elastic properties, lithology and reservoir properties cubes. It makes possible to evaluate uncertainty of prediction.
The authors discuss the case studies of stochastic seismic inversion application in various geological objects of the fields of Rosneft: hard-to-recover reserves of oil of the Bazhen-Abalak complex on the Krasnoleninsky arch, deposits of the lower part of the Pokur suite of the Beregovoye field and the J2 formation of the Tyumen suites in the areas of the Tortasinsky block. The possibility of seismic data stochastic synchronous inversion was determined for structures of highly dissected, laterally sharply variable productive reservoirs. The advantages and limitations of the method are identified. Recommendations for the further development of the method were given. Special 3D seismic data interpretation techniques helping to get elastic and reservoir properties models of formations with complex geological structure which has the same vertical resolution as log data and similar to recorded seismic data. It made possible to solve the problems of clarifying the prospects for the oil and gas content of the target intervals.
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