Structural features and petroleum potential of Jurassic formations in northern Western Siberia

The paper presents the updated data on geostructural features and mode of occurrence of Jurassic deposits in the northern West Siberia; this information in based on the results of sequence stratigraphy analysis of CDP seismic, drilling, and well logging data. The following factors determine geological structure and mode of occurrence of Jurassic series in the northern West Siberia: great depths; repeated regional pattern of sedimentation over the vast areas; large thickness; high values of thermal, depth, and catagenetic parameters of pay intervals; high lithofacies inhomogeneity; abnormal reservoir pressure; less good reservoir quality; higher condensate and solution gas content in gas and oil pools. It is shown that three plays are identified in the Jurassic deposits, they are: Lower-Middle Jurassic (except for Callovian), Callovian-Kimmeridgian, and Tithonian-Berriasian. Petroleum potential of the Jurassic sequences is evaluated. The authors present information on oil and gas occurrence in Zimny, Sharapovsky, Nadoyakhsky, Vymsky, and Malyshevsky reservoirs of the Lower-Middle Jurassic play, Sigovsky reservoir of the Callovian-Kimmeridgian play, and Jurassic-to-Cretaceous Yanovstansky reservoir of Tithonian-Berriasian play. The commercial hydrocarbon potential of the Lower-Middle Jurassic, Callovian-Kimmeridgian, and Tithonian-Berriasian plays is proved. Reliable quantitative estimates of the potential hydrocarbon resources of the Jurassic sequences are not yet available for the vast territory of northern West Siberia. Recommendations for oil and gas prospecting in Jurassic deposits in the northern West Siberia are given. The authors draw attention to new trends of petroleum exploration activities in the Jurassic interval of the section, which are related to the attempts to find various types of non-anticlinal objects at the depths accessible for drilling within the Ob-Laptevsky Ridge and flanks of the West Siberian Sedimentary Basin