The development of oil rims (sub-gas zones) of oil-and-gas and oil-gas-condensate deposits is complicated by the multiphase flow in the formation, which leads to the emergence of negative processes such as pushing oil into the gas zone, breaking gas to the bottom of the producing well (increase in the gas factor is more than 1500 m3/t). As a result, oil recovery does not exceed 10% of the initial reserves.
A potential rise of oil vapor pressure is up to 66.7 kPa, so it is possible to increase a yield of commercial oil due to a change in separation regimes and the extraction of heavy hydrocarbons from low-pressure gas.
If oil vapor pressure exceeds values of 66.7 kPa, two methods for its reduction are possible: additional heating, for example in furnaces, or stripping of light oil components with gas, for example, feeding the first stage separation gas to the separator.
It is established that an increase in the heating temperature in comparison with blowing allows a greater yield of commercial oil, but requires more energy. Thus, when a gas-oil ratio is up to 750 m3/t, it is economically more profitable to heat oil (the profit from additional oil extraction exceeds the cost of energy supply). When the gas-oil ratio exceeds 750 m3/t, the blowing process is preferred in the process of development due to the reduction of energy costs.
A combination of technical solutions and techniques for controlling a pressure of saturated oil vapor allows to reduce losses (increase the yield) of commercial oil.
References
1. Ivanov S.S., Maksimov Yu.V., Features of modeling material and thermal calculation of oil separation process for oil rims (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2016, no. 12, pp. 87–89.
2. Ivanov S.S., Tarasov M.Yu., Zobnin A.A. et al., Oil yield enhancement and reduction of light liquid hydrocarbons content in petroleum gas at oil treatment unit design (Part I) (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2011, no. 8, pp. 138–140.
