Structure, prospects of and potentiality of the Upper Visean - Lower Bashkirian oil and gas bearing carbonate belonging to the southeastern part of the Volga-Ural petroleum province

Stratigraphy and lithology

Article # 36_2023	submitted on 09/13/2023 displayed on website on 09/29/2023
28 p.	Mikheeva A.I.
pdf	Structure, prospects of and potentiality of the Upper Visean - Lower Bashkirian oil and gas bearing carbonate belonging to the southeastern part of the Volga-Ural petroleum province
	The Orenburg region is one of the oldest oil and gas producing regions in Russia and has varying degrees of field depletion. Due to the intensity of exploration and development of predominantly structural traps, the need arose to increase the raw material base through the search and exploration of non-structural objects. One of the important productive petroleum bearing strata in the study area are the Upper Visean - Lower Bashkir carbonates. Based on layer-by-layer sedimentological interpretation of drilling data, biostratigraphical analysis and identification of sedimentary cyclites, well sections were subdivided and correlated, typical sections of various sedimentary zones were compiled and thin-layered models were developed that ran across the strike of facies zones and characterized the spatial relationship of genetic types of sequences. The types of seismic recordings characteristic of the strata of each facies zone were substantiated, a geological interpretation was carried out using a reference network of seismic profiles, and seismic facies maps were constructed for each productive level. Based on these data, lithologic-facies maps and prospect maps of each productive level were developed, and unified oil-prospecting zones were identified for the entire strata as a whole. The study revealed that the formation of the Upper Visean - Lower Bashkirian carbonate petroleum bearing strata in most of the study area occurred in a shallow-water basin of normal salinity with a rugged paleorelief, which determined the full range of facies settings for carbonate accumulation: from lagoons to the lower parts of the slopes of paleotroughs. The presence of reef structures of the barrier system, forward and rear reef trains, rear algal reefs, as well as layers and lenses of clastic limestones of mobile waters of the closed shelf, is a factor of sedimentation prerequisites for the formation of complexly screened (lithological and structural-lithological) hydrocarbon traps in this territory. In addition, of particular interest are the structural and lithological traps in the clinoforms of the side part of the Cis-Ural trough, with which the future prospects of this area are associated. Keywords: Upper Visean - Lower Bashkirian carbonate strata, non-structural hydrocarbon trap, clinoform, oil and gas potential, Orenburg region, southeastern part of the Volga-Ural petroleum Province.
article citation	Mikheeva A.I. Stroenie i perspektivy neftegazonosnosti otlozheniy verkhnevizeysko-nizhnebashkirskogo karbonatnogo kompleksa yugo-vostochnoy chasti Volgo-Ural'skoy neftegazonosnoy provintsii [Structure, prospects of and potentiality of the Upper Visean - Lower Bashkirian oil and gas bearing carbonate belonging to the southeastern part of the Volga-Ural petroleum province]. Neftegazovaya Geologiya. Teoriya I Praktika, 2023, vol. 18, no. 3, available at: http://www.ngtp.ru/rub/2023/36_2023.html EDN: QOZRQN

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