A new method to calculate the early performance of solution-gas-drive reservoirs

Abstract

The performance of gas-solution-drive reservoirs is difficult to figure out since the treatment of highly nonlinear partial differential equations. In previous works, studies about gas-solution-drive reservoirs are restricted to production data analysis and the calculation of performance is almost lacking. The objective of this paper is to propose a novel application of Boltzmann transformation along with an adaptive-size fourth-order Runge-Kutta to figure out the performance of gas-solution-drive reservoirs in early time from the perspective of a well test analysis. Mathematical models about two-phase flow of one-dimensional linear flow and planar radial flow are established respectively. Through solving the governing equations of constant pressure production, the distribution of pressure and saturation at any time can be obtained easily, and curves of pressure and saturation versus time at a specific position can be also achieved. In addition, profiles of gas and oil flow rate at wellbore in terms of time can be acquired. The effect of bottom-hole pressure (BHP) on pressure, saturation and flow rate in early time is investigated. The results obtained from the newly proposed method are compared with numerical simulation results, and comparison results illustrate that the performance of solution-gas-drive reservoirs can be obtained fast and accurately through the new method.