To date, the depletion of conventional reservoirs leads to more attention to difficult low-permeable ones. Mining of rocks with ultra-low reservoir properties always involves a range of issues associated with non-pay low or zero flow rates in wells, low efficiency of the reservoir pressure maintenance system, selecting the best new drilling locations, etc. Resolving these challenges requires a detailed picture of the formation geology and the principles and conditions of its formation. Remodeling the ancient sedimentary environments allows reflecting the reservoir spread patterns and identifying the areas with the best reservoir properties. This study aimed to determine which areas of low-permeable formations were prospective for development. The study subjects were the deposits of the Yu2-1 and Yu2-2 formation groups within the upper subsuite of the Tyumen suite, Middle Jurassic. With frequent interbedding of claystones, sandstones, and aleurolites with coal intercalations, these deposits have complex geology, wide facies variation, low reservoir properties, and significant secondary alterations, which further impair the reservoir properties. In this study, the core examination results allowed us to identify the sedimentary environment and facies of the reservoir rocks. We also retrieved the areal sedimentary environments from the seismic data, found the most prospective facies groups to bring into development, and proposed some options for effective flow initiation and enhancement.
Keywords: FACIES MODEL, YU2 FORMATION, SEDIMENTATION, LOW-PERMEABLE RESERVOIR, CORE EXAMINATION, DIFFICULT RESERVES.