Substantiation of Oil-water Contact in Facies Changeable Upper Jurassic Deposits of the Shirotnoye Priobie Region

The Upper Jurassic deposits are oil-bearing in the study area. The issue of locating the OWC has been revealed in the process of production drilling. The current study approaches the issue of locating the OWC in the scope of the 3D integrated seismic interpretation project. Different types of geological sections for each reservoir have been determined from the well logs and detailed core descriptions. Based on the results of genetic interpretation from the paleodepths analysis, the study of geological-geophysical vertical and lateral heterogeneity of the section, the maps of seismic attributes and acoustic impedance, depositional environments have been identified. The study of reservoir characteristics from the core data enabled discrimination of various reservoir classes. Distribution of these reservoir classes is directly related to geological sections from well logs and depositional environments. The transition zone thickness for different reservoir classes and geological sections from the well log data has been estimated using phase permeability and capillary pressure curves. The oil pool, which had been regarded as one pool according to the previous model, was now divided into several pools characterized by different levels of the oil reservoir. These oil pools are associated with different types of geological sections and depositional environments.