The impact of new geological information on an idea of the hydrocarbon deposits at updating the geological model

In this article, using the example of the “Y”, deposit located in the Russian part of the Northern Caspian Sea, it is shown how the idea of the geological structure of hydrocarbon deposits has changed with the updating of the geological model. It was noted that as of 2017, six wells had been drilled at the “Y” field and a large amount of geological and geophysical information on seismics, drilling, core sampling and analysis, and geophysical and hydrodynamic studies had been accumulated. The obtained results have made changes in the geological structure of the deposits and the filtration-capacitance characteristics of reservoir formations. When updating the petrophysical model of interpretation of the geophysical well surveys (GIS) complex, taking into account new information on the core, there was a change in the parameters of the First stratum of the Tithonian stage. Laboratory studies of the core material made it possible to obtain detailed lithological and petrophysical characteristics of the rocks. Based on the results of biostratigraphic and petrographic studies of the core, studying its material, mineralogical and granulometric composition, a lithological and stratigraphic characteristic of the well section is given, and sedimentation features are revealed. Based on the analysis of the core and the GIS complex, the filtration-capacitance properties and parameters of the reservoirs were characterized and determined, petrophysical dependencies were constructed and adapted to the GIS conditions, the core-GIS dependencies were constructed and the reservoir parameters were substantiated. The propagation intervals of the tire rocks are revealed, and the shielding properties of the overlapping thicknesses are estimated. Based on the new geological and field information, the geological model of the deposit was updated, and the reserves of free gas and condensate in the Tithonsky tier I reservoir of the “Y” deposit were promptly revised and increased by 43%. The redistribution of reserves occurred primarily due to the drilling of new wells, which confirmed the gas content of the northern area and clarified the structural plan of the southern part of the field.