Improving the efficiency of additional development of depleted gas reservoirs by displacing the residual gas with nitrogen

Abstract

Based on the analysis of publications in domestic and foreign scientific and technical publications, the directions of increasing gas recovery from depleted gas reservoirs, which include the displacement of residual gas from the porous medium with nitrogen, are substantiated. Nitrogen can be obtained from the air in any oil and gas producing area using membrane, adsorption or cryogenic types of plants produced by the industry. The final gas recovery factor can be adjusted by choosing certain values ​​of technological parameters that characterize the process of reservoir development. Using hypothetical digital models, the influence on the total final gas recovery factor and the residual gas recovery factor of the pressure of the beginning of nitrogen injection into the reservoir, the rate, duration and cyclicity of its injection, the system for locating production and injection wells on the gas-bearing area and the technological modes of their operation was investigated. The results of the studies are shown in the form of graphical dependencies of the final gas recovery factor and the gas recovery factor for residual gas on the investigated determining parameters. Using the research results, the optimal values ​​of the parameters of the nitrogen injection process into a depleted gas reservoir of square and round shapes and the corresponding values ​​of the gas recovery coefficient have been established. The results of the studies performed indicate a significant technological efficiency of the displacement of residual gas by nitrogen from depleted gas reservoirs. Depending on the system of placement of production and injection wells in the gas-bearing area and the technological parameters of the nitrogen injection process into the reservoir, the gas recovery factor for the residual gas varies on average within the range of 53,97 – 61,82 %.