Mathematical modelling of enhanced gas production

Abstract

Based on a mathematical model for 2D filtration of a two-phase multicomponent hydrocarbon mixture, the boundary problem of optimizing distribution of well flow rates was for the first time composed and solved so as to maximize the gas recovery from a natural gas reservoir at its final stage of development. The input data used in the model are the planned gas production in the reservoir and reservoir characteristics (its thickness, porosity, and permeability). The flow rate optimization in individual wells is carried out in such a way that the pressure drop is kept constant for the recharge area of each well. The proposed optimization algorithm takes into account both the restriction on the flow rates in certain wells and their shutoffs for remedial maintenance. The own computer program has been developed to solve the problem. The efficiency of this approach is illustrated by the example of the natural gas reservoir Kotelevske (Ukraine). It is shown that the control of the pressure equalizing process in the recharge area of each well leads to the decrease in differential pressure inside the whole reservoir. As a result, the 6% increase in gas production was possible for the optimum alternative in a shorter period of time. Keywords Natural gas reservoir • Enhanced gas production • Optimization of reservoir development • Mathematical model n , n Coordinates of the n th well, m g , w Gas and liquid phase viscosities, respectively, kg/m c g , w Gas and liquid phase densities, respectively, g/m 3 std g,k Density of the k th component under standard conditions, g/m 3 std g