A method for choosing a gas agent and an approach to assessing the possible results of gas injection for one of the fields of the Central Khoreyver uplift confined to carbonate reservoirs is described. Several gas compositions were tested as injection agents: inorganic individual compounds (nitrogen, carbon dioxide, methane) and mixtures of hydrocarbon gases with different mole fraction of methane and "fat" components (C2-C4). To evaluate the effectiveness of the selected compositions, experiments were performed on a Slim Tube formation model under thermobaric formation conditions (pressure – 30 MPa, temperature – 67 °C). A detailed description of the experimental unit of Slim Tube is given. A theoretical assessment was also made of the degree of miscibility of gas agents and oil in situ using a triple diagram based on a tuned PVT formation fluid model. Due to the limited reserves of flare gas and a decrease in its available volumes in the future, the option of pumping the gas rim with the highest content of “fat” components and then displace it with nitrogen with different sizes of the rim of “wet” gas (15 and 30% of the pore volume) was considered. The use of such gas rims leads to a significant reduction in the cost of gas exposure with a slight decrease in the coefficient of oil displacement. The displacement rate when using 30 % of the pore volume of the rim of the "wet gas" fell by only 2.5 % compared with the use of pure "wet" flare gas.
The article gives a preliminary assessment of the effectiveness of using various formulations of displacement agents. The joint conduct of filtration experiments and calculations on the PVT model made it possible to significantly reduce the amount of experimental work with a simultaneous increase in their information content.
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