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Polyacrylamide-based formation treatment technologies have been extensively used to enhance oil recovery at the field operated by Tatneft. These are applicable under various geological conditions encountered at the Company’s fields; particularly, they may be used in terrigenous Devonian and Carboniferous deposits and carbonate reservoirs. They help to address a wide range of challenges: from water shut-off operations in production wells to conformance control treatments in injection wells. Extensive research efforts have led to development of two promising technologies: water shutoff technology relying on application of high strength polymer systems and EOR technology involving injection of high-strength cross-linked compositions to enhance production from heterogeneous waterflooded formations. These technologies are based on application of polyacrylamide and complex cross linker to produce a cross-linked polymer system (gel) exhibiting high shear strength under reservoir conditions. Laboratory studies of the effects of water composition on formation of cross-linked polymer compositions and stability of the resultant gel systems have been conducted to improve the performance of the above mentioned methods and other polyacrylamide-based technologies. The research consisted in taking samples of formation water from selected fields operated by nine oil-and-gas production departments of TATNEFT Company and a number of studies and experiments. These included determination of the composition of formation water (six-membered analysis, total salt content, content of hydrogen sulphide, and iron content); determination of the impact of water composition on viscosity and screen-factor of polymer solutions; preparation of cross-linked polymer systems with each type of analyzed formation water and examination of gel stability under near real reservoir conditions. Based on the analysis and summary of the results obtained, possible solutions for reduction of adverse effects of negative factors on the performance of cross-linked polymer systems have been through out together with recommendations on mitigation of such effects. References 1. Beregovoy Ant. N., Rakhimova Sh.G., Vasil'ev E.P., Afanas'eva O.I., Belov V.I., Razumov A.R., Rezul'taty primeneniya kompleksa tekhnologiy VPSD dlya ogranicheniya vodopritoka v dobyvayushchie skvazhiny (Results of application of high-strength polymer systems for water shut-off), Proceedings of TatNIPIneft' / PAO “Tatneft'”, 2017, V. 85, pp. 264-272. 2. Beregovoy Ant. N., Vasil'ev E.P., Uvarov S.G., Afanas'eva O.I., Belov V.I., Razumov A.R., Yartiev A.F., Rezul'taty primeneniya tekhnologiy uvelicheniya nefteizvlecheniya v zavisimosti ot geologo-fizicheskikh usloviy na primere tekhnologiy GES-M, VPSK (Results of application of technologies for increasing oil recovery depending on geological and physical conditions on the example of a hydrophobic emulsion composition and high-strength polymer systems), Proceedings of TatNIPIneft' / PAO “Tatneft'”, 2017, V. 85, pp. 238-248. 3. Patent no. 2382185 RF, MPK E 21 V 43/22, C 09 K 8/90, Method for injection well infectivity profile aligning and water in-flow limitation for production well (Versions), Inventors: Ibatullin R.R., Amerkhanov M.I., Rakhimova Sh.G., Beregovoy A.N., Zolotukhina V.C., Latypov R.R., Khisamov R.S. 4. Patent no. 2424426 RF, MPK E 21 B 43/22, C 09 K 8/90, Procedure for development of non-uniform reservoir, Inventos: Amerkhanov M.I., Beregovoy A.N., Rakhimova Sh.G., Zolotukhina V.S., Fayzullin I.N., Vasil'ev E.P. 5. Patent no. 2431741 RF, MPK E 21 V 43/22, Procedure for development of non-uniform reservoir, Inventors: Ibatullin R.R., Amerkhanov M.I., Beregovoy A.N., Rakhimova Sh.G., Khisamov R.S., Fayzullin I.N., Farkhutdinov G.N.
6. Burdyn' T.A., Zaks Yu.B., Khimiya nefti, gaza i plastovykh vod (Chemistry of oil, gas and formation water), Moscow: Nedra Publ., 1975, 215 p. |
