Enhanced oil recovery methods applied for under-gas-cap heavy oil rims

UDK: 622.276.6

Key words: under-gas-cap rims, high-viscosity oil, enhanced oil recovery (EOR), the technology of field development

Authors: A.V. Arzhilovskiy, V.V. Vasilyev, N.N. Ivantsov, K.G. Lapin (TNNC LLC, RF, Tyumen), Toropov K.V. (Rosneft Oil Company PJSC, RF, Moscow)

Development of thin under-gas-cap rims is associated with high risks of gas breakthrough fr om the gas cap into production wells. This challenge becomes many times heavier in high-viscosity oil rims, wh ere the gas breakthrough might completely stop the oil inflow into the wellbore. A case study of PK_1-2 reservoir of Van-Eganskoye Field was used to analyze ways to improve heavy oil recovery from under-gas-cap rims: sectional completion of horizontal wells and installation of inflow control devices, limiting the drawdown, flexible well control, injection into injection wells before the production wells start to operate, infill drilling, as well as gas production from gas caps to prevent gas coning. Simultaneous use of these approaches can represent a comprehensive technology for under-gas-cap rims development. The technology parameters were selected and its performance was assessed using sector flow simulation models in CMG STARS. The model runs were performed for a variety of specific formation zones which differ in oil- and gas-saturated thickness, number of permeable layers, and bedding angles. The results of model runs show that this technology greatly improves the prospects for the successful operation of thin under-gas cap heavy oil rims under high geological heterogeneity. The technology in general or its individual components can be applied either at the design stage or at the optimization stage of development.
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