Identification of oil deposits for prevention of potential production problems resulting from phase transitions in oil

UDK: 622.276.1/.4.001 + 552.578.2

DOI: 10.24887/0028-2448-2020-7-30-32

Key words: oil viscosity, oil fields development, structural phase transition in oil

Authors: V.М. Khusainov (TatNIPIneft, RF, Bugulma), О.S. Sotnikov (TatNIPIneft, RF, Bugulma), А.Kh. Kabirova (TatNIPIneft, RF, Bugulma), I.F. Galimov (Oil and Gas Production Department Leninogorskneft, RF, Leninogorsk), М.Т. Khannanov (Oil and Gas Production Department Yamashneft, Almetyevsk), М.А. Sayfutdinov (Oil and Gas Production Department Nurlatneft, RF, Almetyevsk)

At the current stage of fields development in Tatarstan, the key approaches to replacement of oil reserves entail bringing into development oil fields and deposits with high content of multicomponent heavy hydrocarbons and enhancing the production from poorly drained reservoirs containing oil reserves with similar characteristics. The present research effort aims to identify oil accumulations in Carboniferous sediments of the Republic of Tatarstan to predict potential production problems under conditions favorable for structural phase transition in oil. Phase transition can occur in case of changes in oil composition and pressure/temperature conditions in the course of field development. In-situ conditions of oil reservoirs confined to Carboniferous sediments (depth of occurrence, reservoir temperature) and physical/chemical properties of hydrocarbons (composition, viscosity, temperature of phase transition) can cause this problem, particularly during cold water injection for reservoir pressure maintenance. The structure of the remaining oil reserves in the Republic of Tatarstan suggests priority of bringing into development of the Carboniferous oil reservoirs. Investigation and understanding of phase behavior of oil components is still a very important and large-scale task. Identification of oil deposits associated with potential production problems due to phase transition will enable economic development of Carboniferous reservoirs. The analysis has covered 162 oil fields in the Republic of Tatarstan, which comprise 766 oil deposits across the entire sedimentary cover. Of these, 76.5% are confined to Carboniferous sediments. The number of Carboniferous reservoirs is almost equally distributed between Tatneft and other oil companies of Tatarstan, with 71% of Tatneft’s assets found on production sites of oil and gas production departments Leninogorskneft, Yamashneft, and Nurlatneft. Results of the analysis have demonstrated that production assets of Tatneft and other Tatarstan oil producers contain reservoirs with potential phase-transition-related production problems. Oil producers whose production targets are at the risk are presented. References 1. Mansoori G.Ali., Phase behavior in petroleum fluids (A detailed descriptive and illustrative account), Encyclopedia of Life Support Systems, 2009, 33 p., URL: https://www.eolss.net/Sample-Chapters/C08/E6-185-03.pdf 2. Kabirova A.Kh., Khusainov V.M., Structural phase transition and necessity to consider this phenomenon in projects of heavy oil fields development (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2018, no. 7, pp. 32–34. 3. Khusainov V.M., Struktura ostatochnykh zapasov Tatarstana. Problemy i perspektivy razrabotki (Structure of residual reserves of Tatarstan. Problems and prospects of development), Collected papers “Trudnoizvlekaemye i netraditsionnye zapasy uglevodorodov: opyt i prognozy” (Hard-to-recover and unconventional hydrocarbon reserves: experiences and forecasts), Proceedings of International scientific and practical conference, Kazan: Fen Publ., 2014, 2014, pp. 86–89. 4. Khamidullin F.F., Amerkhanov I.I., Shaymardanov R.A., Fiziko-khimicheskie svoystva i sostavy plastovykh neftey pri differentsial'nom razgazirovanii na mestorozhdeniyakh Respubliki Tatarstan (Physico-chemical properties and compositions of reservoir oils during differential degassing in the fields of the Republic of Tatarstan), Kazan: Master Layn Publ., 2000, 344 p. 5. Muslimov R.Kh., Abdulmazitov R.G., Khisamov R.B. et al., Neftegazonosnost' Respubliki Tatarstan. Geologiya i razrabotka neftyanykh mestorozhdeniy (Oil and gas bearing of the Republic of Tatarstan. Geology and development of oil fields), Part 1, Kazan': FEN Publ., 2007, 316 p.