The main oil reserves of Tatneft PJSC have entered the mature stage with more than 80% of oil in place original oil-in-place having been recovered. More than half of oil comes from the depleted sandstone reservoirs with recoverable reserves steadily declining. The share of hard-to-recover reserves in the Company’s assets’ structure is more than 78%. However, production enhancement operations carried out by the Company on a wide scale help to maintain a stable level of oil production. Enhanced oil recovery (EOR) technologies are not able to provide for the maximum oil recovery unless concrete geological environment and reservoir properties are given intense attention. The Company has been successfully developing and introducing own EOR technologies that meet the challenging in-situ conditions. Novel oil recovery processes extend reservoir life, which is particularly important under the volatile market conditions. The depleted reservoirs developed by waterflooding still have a considerable potential, and chemical flooding is one of the most effective ways to displace the residual reserves. A great number of different chemical EOR methods have been tested and applied in the Company’s fields, however, just few technologies have proved the most effective. One of the technologies that really work is injection of hydrophobic emulsion systems. The works started at TatNIPIneft more than ten years ago. Since then, a large number of different compositions and injection methods have been tested in laboratory and in field.
Currently, emulsion-based technologies loom large in chemical EOR portfolio of the Company. The full technology cycle has been developed, from the QA production of emulsifying agent, preparation of compositions for injection, and application of the technology in a wide range of geological and reservoir conditions.
References
1. Patent no. 2153576 RF, MPK E 21 V 43/22, Reverse emulsion for treating oil strata, Inventors: Seleznev A.G., Kryanev D.Yu., Makarshin S.V.
2. Patent no. 2110675 RF, MPK E 21 V 43/22, Invert microemulsion for treating oil beds.
3. Patent no. 2379326 RF, MPK C 09 K 8/584, Water repellent emulsion for oil reservoirs treatment, Inventors: Ibatullin R.R., Amerkhanov M.I., Rakhimova Sh.G., Beregovoy A.N., Andriyanova O.M., Khisamov R.S.
4. Beregovoy A.N., Amerkhanov M.I., Rakhimova Sh.G., Vasil'ev E.P., Application of invert emulsions enhances conformance in heterogeneous formations (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2010, no. 8, pp. 116–118.
5. Patent no. 2613975 RF, MPK V 01 F 17/00, C 09 K 8/00, C 11 D 1/04, 3/43. Invert emulsions emulsifier, Inventors: Sakhabutdinov R.Z., Beregovoy A.N., Rakhimova Sh.G., Andriyanova O.M., Fadeev V.G., Amerkhanov M.I., Nafikov A.A.
6. Patent no. 2660967 RF, MPK E 21 V 43/22, C 09 K 8/92, E 21 V 43/16, Method of treating non-uniform permeability oil reservoir by injection of invert emulsion, Inventors: Zaripov A.T., Beregovoy A.N., Rakhimova Sh.G., Medvedeva N.A., Lakomkin V.N., Amerkhanov M.I., Nafikov A.A.
