INFLUENCE OF THE SYSTEM OF PRODUCTION AND INJECTION WELLS AREAL PLACING WHILE INJECTING NITROGEN INTO THE DEPLETED GAS RESERVOIR ON THE GAS RECOVERY RATIO

Abstract

The results of experimental and theoretical studies of the displacement of residual natural gas from the depleted gas deposits by non-hydrocarbon gases are analyzed, and the use of nitrogen as a displacing agent is substantiated. The authors present results of computer studies of areal injection of nitrogen into a hypothetical depleted gas reservoir at 4-, 5-, 7- and 9-point well placing systems in the gas-bearing area and the distance of 500, 750, 1000 and 1250 m from the central injection well to peripheral production wells.
 The article designates the significant influence of the well placing system in the gas-bearing area and thedistance between the injection and production wells on the gas recovery ratio as to residual gas and on the duration of the further reservoir development period until the moment when nitrogen breaks through into production wellsand the nitrogen content in the formation product is 5 % vol. The research has got a wide range of changes in their values (from 6.92 to 56.44 % for the gas recovery ratio at the time of nitrogen breakthrough into production wells, from 4 to 49 months for the duration of the additional reservoir production process). It gives possibilities to optimize the system of production and injection wells placing in the gas-bearing area, taking into account the technological and techno-economic indicators of further reservoir development. The results are recommended to use when designing the areal injection of nitrogen for a real depleted gas reservoir.