This paper discusses the use of geophysical well logging for the interpretation of complex structure oil-saturated intervals of the Lower and Middle Jurassic horizons with high average number of permeable intervals, the content of minerals — semiconductors (pyrite, siderite, glauconite, et al.) for structuring a complex of geological and geophysical information and developing a researching methodology of areas with hard to recover reserves on example of deposits which was in operation for an extended period of time.
The issues of improving the efficiency of processing the results of studies of the filtration properties of reservoirs within the oil and gas producing areas of the central part of the West Siberian oil and gas province are considered. The high degree of development of the hydrocarbon resources of the studied territory is characterized by the presence of long-term developed deposits, which determines the solution of tasks aimed at increasing the success of the search for complex deep-lying reservoirs, the efficiency of their exploration and additional exploration, since the overlying productive horizons are practically developed. This task is one of the most important at the current stage of field development in this region, in the context of falling oil production at the main large fields, and has no unambiguous solution.This article covers the issues of reservoir modeling using new scientific and methodological approaches to the processing of geophysical data and the possibility of using modern software products when grouping development objects according to criteria corresponding to a reservoir of a certain lithotype. This approach allowed us to build high-quality geological models and justify the use of the most effective complex of geophysical studies for modeling low-amplitude (no more than 15 m) and small-sized (less than 20 km2) oil deposits. In the course of research: The results of the reservoir filtration properties were processed; low-amplitude and small-size sediments of channel sediments (river valleys) were established; the industrial oil and gas content of complex sediments characterized by low-amplitude and small-size sediments (Tyumen formation, object Ю2) was proved; The interpretation of geophysical studies of wells was carried out, the results were compared with the energy characteristics of the reflected waves (seismic studies), zones saturated with water-oil-gas fluid were established (3D models were built), and the possibility of using this technique for identifying and mapping complex deep oil deposits was shown.
There were examined the issues of studying the features of the lithological and petrographic composition and the formation of oil deposits within the fields of the Surgut dome fold and the Frolov megadepression. It was noted that the formation of deposits of the sedimentary cover is associated with the peculiarities of the geological structure and the oil-bearing capacity of the basement rocks. In the considered territory, a high level of oil-bearing sedimentary cover is observed within the central part of the Surgut dome fold, and the deposits of the Pre-Jurassic part of the section can be additional sources of intensification of hydrocarbons in the Lower-Middle Jurassic deposits. The presence of zones of deep snaps is a search criterion for the detection of secondary reservoirs in them both — in destruction zones, basement, and in the Lower-Middle Jurassic deposits, therefore, deposits can be formed due to the vertically ascending migration of deep fluids through faults that cross the basement and horizons of the sedimentary cover.There were examined the issues of the prospects for the oil and gas content of the Lower-Middle Jurassic deposits, which must be associated with both granitoid massifs and the details of identifying the conditions of sedimentation and the establishment of contact zones of the sedimentary cover with the underlying formations.
