The article presents the lithological and geochemical characteristics of potential oil source rocks on the example of one of the wells on the eastern side of the Caspian depression. According to the complex of geological and geophysical data, several large strata were identified, lithotypes enriched in organic matter (OM) were selected based on core and pyrolytic data. Structural-textural and mineral-material features of rocks largely determine the nature of organic matter distribution. The authors presented a detailed lithological description of various lithotypes, determined the amount and patterns of distribution of organic matter, maturity level and, as a result, the oil source potential of a particular rock. The article introduces a detailed lithological description of the section of one of the deep wells of the pre-salt complex of the Upper Paleozoic. Due to a detailed study of the core material, characteristics that allowed making an assumption about attributing of certain strata to potential oil source intervals were determined.
The study of rocks was conducted by optical microscopy with the identification and description of lithotypes, with special attention paid to the nature of the distribution of organic matter in the rock. The Rock-Eval method was used to determine the generation potential of the rocks. The article presents data on the main geochemical parameters - the total organic carbon in the rock, the hydrogen index and the temperature corresponding to the maximum yield of hydrocarbons in the S2 peak (the residual generation potential of the rock). As a result, the classes of oil source rocks, the type of kerogen and the stage of maturity of organic matter were measured.
The results can be correlated with the intervals of occurrence of rocks of similar lithotypes in the similar strata in the wells section that were not characterized by a core.
References
1. Antipov M.P., Bykadorov V.A., Volozh Yu.A. et al., Osobennosti stroeniya Priural’skoy kraevoy sistemy Vostochno-Evropeyskogo kontinenta v svyazi s neftegazonosnost’yu (Features of the structure of the Urals regional system of the East European continent in connection with the oil and gas potential), In: Neftegazonosnye basseyny Kazakhstana i perspektivy ikh osvoeniya (Oil and gas bearing basins of Kazakhstan and prospects for their development), Almaty: KONG Publ., 2015, pp. 264–280.
2. Abilkhasimov Kh.B., Characteristics of oil and gas accumulation zones and features of the location of natural reservoirs in the Paleozoic complex of the Caspian depression (In Russ.), Geologiya i okhrana nedr, 2011, no. 3(40), pp. 35–47.
3. Miletenko N.V., Fedorenko O.A., Atlas litologo-paleogeograficheskikh, strukturnykh, palinspaticheskikh i geoekologicheskikh kart Tsentral’noy Evrazii (Atlas of lithological-paleogeographic, structural, palinspatic and geoecological maps of Central Eurasia), Almaty: Publ. of YuGGEO, 2002.
4. Savel’eva O.L., Savel’ev D.P., Chubarov V.M., Pyrite framboids in carbonaceous rocks of Smaginassotiation in the Kamchatsky Mys peninsula (In Russ.), Vestnik kamchatskoy regional’noy organizatsii Uchebno-nauchnyy tsentr. Ser. Nauki o Zemle, 2013, no. 2(22), pp. 144–151.
5. Postnikov A.V., Musikhin A.D., Osintseva N.A. et al., Influence of rocks pore structure on deposits development of Khadum formation in East Caucasian region (In Russ.), Geofizika, 2016, no. 6, pp. 30–38.
6. Iskaziev K.O., Savinova L.A., Almazov D.O., Lyapunov Yu.V., Prospects of oil and gas potential of deep-water Lower Permian deposits within the eastern part of the Pre-Caspian basin (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2021, no. 5, pp. 22–25, DOI: https://doi.org/10.24887/0028-2448-2021-5-22-25
