Peculiar aspects related to extraction of oil and gas from Sargaevskian sediments based on the example of Tatneft PJSC

UDK: 553.98.061.4:552.54

DOI: 10.24887/0028-2448-2020-7-16-20

Key words: Sargaevskian horizon, Domanic sediments, oil-source rocks, oil inflow, hard-to-recover reserves

Authors: R.S. Khisamov (Tatneft PJSC, RF, Almetyevsk), N.А. Nazimov (Tatneft PJSC, RF, Almetyevsk), V.V. Emelyanov (Tatneft PJSC, RF, Almetyevsk), V.G. Bazarevskaya (TatNIPIneft, RF, Bugulma), О.G. Gibadullina (TatNIPIneft, RF, Bugulma)

Currently, Tatneft devotes special attention to studies of unconventional hydrocarbon sources that contain hard-to-recover reserves. Unconventional sources of hard-to-recover reserves comprise cost-intensive and poorly accessible hydrocarbon-bearing formations. In the Republic of Tatarstan, these are Frasnian-Famennian productive Domanic sediments exhibiting low-quality reservoir properties. Domanic sediments are represented by siliceous-argillaceous-carbonate varieties enriched with organic matter and other dissipated oil components. Domanic deposits of Sargaevskian, Semilukskian-Mendymskian, Eletskian, Dankovo-Lebedyanskian, and Zavolzhskian horizons were proved to be oil-bearing. Petroleum potential of Sargaevskian sediments was confirmed within particular areas in the Southeast of the Republic of Tatarstan. The most promising exploration targets within the Sargaevskian horizon are confined to Saraylinskoye, Bondyzhskoye, Pervomaiskoye, Baskrykskoye, and Zychebashskoye fields. The article continues the publication series related to study of petroleum potential of the Domanic sediments of the Volga-Ural petroleum province. The authors consider the issues of identification and extraction of hydrocarbons from potentially oil-bearing intervals of the Sargaevskian horizon associated with Frasnian-Famennian carbonate complex; selection of candidate wells and test intervals; and highlights well stimulation technologies: particularly, hydraulic fracturing and massive acid fracturing. Attempts to investigate Sargaevskian oil genesis in the territory of Tatneft’s activities are undertaken. Laboratory studies (particularly using geochemical methods) of Sargaevskian core samples have indicated that these rocks have low permeability and contain organic matter in excess of 1 %. This meets the criteria established in Provisional Guidelines for Estimation of Oil Reserves in Productive Domanic Sediments and used for ranking of potential production targets to include them to a category of the hard-to-recover. Pilot operations conducted within the Bonduzhskoye field provided the evidence of oil presence in Sargaevskian sediments. However, oil extraction presents many challenges and calls for unconventional approaches, and further studies, which, in turn, affects the economic performance of oil production. Consequently, necessity for continuing detailed research of Sargaevskian sediments is obvious. It will require application of conceptually new, special-purpose methods for identification and development of production targets.