Analysis of Factors Affecting Bottom Hole Pressure in Tight Gas Reservoir

Abstract

In order to solve the problem of low accuracy of bottom hole pressure in tight gas reservoir, this paper presents a new way to analyze the bottom hole pressure. By combining literature research and starting from nonlinear motion equations, the model of bottom hole pressure was established through using various mathematical methods such as separation variable method, identity transformation method and differential discrete method. This paper presents a high-precision and high-efficiency method for solving bottom hole pressure in tight gas reservoirs, and a dynamic calculation method for permeability and conductivity is given. Through the sensitivity analysis of the influencing factors of dimensionless pressure and pressure derivative, it is concluded that the larger the power law index is, the larger the warpage of the dimensionless pressure and pressure derivative curve is. The larger the skin coefficient and the wellbore storage coefficient is, the earlier the fluid enters into the quasi-steady-state seepage. When the tight gas reservoir contains closed edges, the resolution points of the dimensionless pressure and pressure derivative curves are obvious with crossing. On the contrary, when the tight gas reservoir contains the constant pressure boundary, the resolution points of the dimensionless pressure and pressure derivative curves are not obvious without crossing.