Study of the features of the formation, structure and hydrocarbon potential accounting of the Upper Cretaceous oil-water deposits (the Eastern Ciscaucasia)

UDK: 553.98
DOI: 10.24887/0028-2448-2022-3-12-16
Key words: underformed deposit, Upper Cretaceous, Paleogene, Eastern Stavropol, permeability, well testing, hydrophobicity, oil-generating parent rocks, well logging, chalk-like limestone, caven-fractured reservoir
Authors: A.A. Brailovskaya (NK Rosneft-NTC LLC, RF, Krasnodar), M.A. Naumova (NK Rosneft-NTC LLC, RF, Krasnodar), V.M Yatsenko (Rosneft Oil Company, RF, Moscow)

Scientists have been interested in studying the lithological composition, geological structure and stratification of sections, reservoir properties, saturation, conditions and history of the development of Upper Cretaceous deposits (K2) of the Eastern Caucasus for more than 70 years. The problem of further study of Upper Cretaceous deposits and associated hydrocarbon deposits is very complex and relevant. In previos work the authors showed the similarities and differences of the geological structure and conditions of the development of Upper Cretaceous deposits within a number of regions of the Eastern Caucasus: Eastern Stavropol, the Republique of Ingushetia, and the Chechen Republic. The deposits are differentiated by the depths of their occurrence, the conditions of formation and maturity, the types of reservoirs, the presence of discontinuous faults, the intensity and composition of fluid inflows. The formed mature high-amplitude (over 250-500 m), complicated by discontinuous disturbances of various order, including intrawater dislocations, Upper Cretaceous traps of the Chechen Republic and the Republique of Ingushetia are characterized by initial fluid flow rates up to 200-3000 t/day and practically anhydrous hydrocarbons tributaries. For low-amplitude (less than 50 m) underformed deposits of Eastern Stavropol and Plain Dagestan, not rich in intra-water faults, less representative fluid flow rates (more often under 100-150 t/day) with a high water content at all stages of development are characteristic. The tendency of the dependence of the intensity and composition of tributaries on the amplitude of Upper Cretaceous deposits and a number of other factors was traced by the authors within the Eastern Stavropol territory. The differentiation of "non-standard" traps of the region according to the features of the lithological and stratigraphic structure, the potential of carbonate reservoirs, taking into account the tectonic, geochemical and geological prerequisites for their formation, is carried out.

In this article specialists of Rosneft Company and its subsidiary Rosneft-NTC have identified and analyzed the signs of the most promising Maastricht zones of the Eastern Stavropol Region that are relevant when searching for missed traps, planning well interventions and contributing to improving the efficiency of the Company's field development. These features can be applied to other oil and gas bearing areas with similar geological conditions. Also, recommendations are given for optimizing the development processes of immature hydrocarbons deposits in carbonate cavern-crack rocks.

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