Yurubcheno-Tokhomskoe major oil-gas-condensate field in Eastern Siberia is unique and has no analogues in the world. The article considers qualities of its reservoir structure. Results of integrated exploratory and production drilling analysis are presented. Main success factors are identified based on seismic data analysis, well logging, production logging, well testing, field development history and current geological concepts.
A complex structure of Yurubcheno-Tokhomskoe field is conditioned by a plenty of deposits with different oil-water and gas-oil contacts of two uneven geological complexes. The Riphean reservoir consists of carbonate non-permeable matrix with many capacity components presented as fractures and caverns. Also there are multiple discontinuities in reservoir section, intense variability of roof altitude connected with the presence of paleocuts. Vendian geological complex deposits are highly dissected and have small effective reservoir thickness. The main component of the reservoir capacity is cavernosity. According to that fact, an important goal is the most intensive leaching zones prediction. Cavernous intervals are confined to roof part of Riphean and paleocuts slopes. In addition, there is observed degradation of filtration and capacitive properties to the bottom of Riphean sediments. An important factor influencing the operation is the location of the horizontal wellbore relative to fractures and macrofractures, which provoke breakthroughs of the underlying water and gas of the vast gas cap. In the most cases, unsuccessful production wells are located in the north part of the deposit. There is small effective capacitance and lack of caverns in oil saturated part of the reservoir. Successful production wells are drilled to high-capacitance zones, mostly consisting of cavernous component and in 70% of cases they are located nearby paleocuts.
References
1. Bagrintseva K.I., Krasil'nikova N.B. et al., Formation conditions and properties of the Riphean carbonaceous reservoirs of the Yurubcheno-Tokhomsk deposit (In Russ.), Geologiya nefti i gaza, 2015, no. 1, pp. 24–40.
2. Kutukova N.M., Rekonstruktsiya geologicheskogo stroeniya, usloviy formirovaniya i prognoz uglevodorodnykh skopleniy rifeyskikh otlozheniy Kamovskogo svoda Baykitskoy anteklizy Vostochnoy Sibiri: na primere Yurubcheno-Tokhomskogo mestorozhdeniya (Reconstruction of the geological structure, formation conditions and forecast of hydrocarbon accumulations of the Riphean deposits of the Kamovsky arch of the Baikit anteclise in Eastern Siberia: on the example of the Yurubcheno-Tokhomsky field): thesis of candidate of geological and mineralogical science, Moscow, 2020.
3. Afanas'ev I.S., Antonenko D.A., Kutukova N.M. et al., System optimization of design solutions for the development of Yurubcheno-Tokhomskoye field (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2011, no. 6, pp. 10–13.
