Merkulov 2-2024

O.I. Merkulov, V.P. Stenin, S.Yu. Malyavin, V.B. Shcheglov, S.V. Sizintsev

Lower Permian subsalt deposits of the Astrakhan arch: promising focus area for oil and gas exploration in south-west of Caspian region

DOI 10.47148/0016-7894-2024-2-29-40

Key words: Caspian Depression; Astrakhan Arch; Lower Permian deposits; oil; gas; petroleum potential; hydrocarbon resources; focus areas of geological exploration; subgranular reservoir; shale gas; shale oil.

For citation: Merkulov O.I., Stenin V.P., Malyavin S.Yu., Shcheglov V.B., Sizintsev S.V. Lower Permian subsalt deposits of the Astrakhan arch: promising focus area for oil and gas exploration in south-west of Caspian region. Geologiya nefti i gaza. 2024;(2):29–40. DOI: 10.47148/0016-7894-2024-2-29-40. In Russ.

For several decades, field of work related to prospecting for oil, oil and gas, and oil and gas condensate accumulations in the Lower Permian subsalt series of the Astrakhan Arch has remained omitted. Drilling exploration and production wells at the Astrakhan gas condensate field resulted in obtaining hydrocarbon commercial inflows and shows in the lower Perm subsalt interval. According to lithological composition and features of oil and gas accumulation in the Lower Permian subsalt interval, two sequences are clearly distinguished, namely: Lower Asselian–Sakmarian-Artinskian and Upper Filippovsky. First of them is represented by siliceous-argillaceous-carbonate deposits, and can be considered as a source of shale gas and shale oil. The Filippovsky part is represented by carbonate formation with complicated distribution of reservoir properties. Hydrocarbon resource potential of these deposits in the study area is estimated at 413.4 MMTOE including 350.3 MM tons of oil and 55.8 BCM of free gas. Because of the occurrence of active and highly organic-reach oil and gas source series in the Lower Permian interval, prediction of reservoir development and distribution will be a key aspect of prospecting and appraisal works. Structural factor will not be decisive in planning exploration and prospecting activities.