The Republic of Tatarstan possesses considerable high- and ultra-high viscosity oil reserves. The latter are localized at relatively shallow depths (primarily up to 200 m), but fall under the category of hard-to-recover due to high viscosity reaching in-situ as high as 100 Pa·s and even higher. High-viscosity oil fields are developed under conventional natural drive utilizing the reservoir energy or under waterflood, that fail to provide high oil recovery factors. Ultra-viscous oil is recovered using thermal methods. Steam-assisted gravity drainage is the most extensively used method in Tatneft Company. Although this technology has already proven its efficiency, various factors affect ultra-viscous oil production in the Company: complex geological structure of the fields (small thicknesses, heterogeneous structure with low-permeability shale interlayers, vertical and horizontal variations in oil saturation and permeability, moving oil-water contact); vertical viscosity variations; substantial costs associated with steam generation and injection; considerable expenses on treatment of produced fluid. These factors are detrimental to the economics of ultra-viscous oil field development projects that often are rendered unprofitable without tax incentives. Chemical (thermal-chemical) treatments may improve economic efficiency of high- and ultra-high viscosity oil production, when heat and steam generation does not require considerable costs. In light of the above, assessment of applicability of chemical agents and compositions thereof to enhance the efficiency of high-viscosity field development becomes of utmost importance.
References
1. Wilson A., Pelican lake: First successful application of polymer flooding in a heavy-oil reservoir, Journal of Petroleum Technology, 2014, December, 31, URL: https://jpt.spe.org/pelican-lake-first-successful-application-polymer-flooding-heavy-oil-reservoir
2. Akhmetzyanov F.M., BeregovoyAnt. N., Knyazeva N.A. et al., Problemy razrabotki zalezhi sverkhvyazkoy nefti s perekhodnymi (vodoproyavlyayushchimi) zonami plasta (Problems of development of extra-viscous oil deposits with transitional (water-producing) formation zones), Proceedings of TatNIPIneft' / PAO Tatneft', 2021, V. 89, pp. 139–144.
3. Rakhimova Sh.G., Amerkhanov M.I., Andriyanova O.M., Latypov R.R., Fil'tratsionnye issledovaniya vliyaniya kompozitsiy neionogennykh poverkhnostno-aktivnykh veshchestv i rastvoriteley na effektivnost' vytesneniya vysokovyazkoy nefti (Filtration studies of the effect of compositions of nonionic surfactants and solvents on the efficiency of high-viscosity oil displacement), Proceedings of TatNIPIneft' / PAO Tatneft', 2012, V. 80, pp. 162–166.
4. Massarweh O., Abushaikha A.S., The use of surfactants in enhanced oil recovery: A review of recent advances, Energy Reports, 2020, V. 6, pp. 3150–3178, DOI: https://doi.org/10.1016/j.egyr.2020.11.009
