Theoretical Model Research And Software Development Of Well Test Analysis For Multi-stage Fracturing Horizontal Wells In Shale Gas Reservoirs

Unconventional resources such as shale gas have become the focus of the oil and gas resources development in the world. The development of shale gas is so urgent recently. However, studies for shale gas reservoir percolation mechanism and well testing theory are insufficient so far, therefore the well test curves of shale gas cannot be accurately explained.Based on a great deal of literature in home and abroad, this paper presents a more improved well test analysis theory model for multi-fractured horizontal well of shale gas reservoir, and a relevant software is developed, which provides the necessary technical means for understanding and evaluating the shale gas reservoir better. The main contents are as follows:(1) Based on literature research achievement, the paper analyzes the micro-porosity structure, the seepage and storage characteristics in shale gas reservoir, and understand its output and the migration mechanism.(2) The basic seepage model of shale matrix system is establish considering adsorption-desorption, diffusion, percolation behavior and stress-sensitive effects, and then the seepage differential equations in dual-porosity formation are derived under the steady and transient conditions respectively.(3) A multiple fractured horizontal well in shale gas reservoir is simplified as three linear flow and five linear flow model on the analysis of occurrence of shale gas, flow mechanism and micro-seismic monitoring of shale gas. Mathematical three linear flow and five linear flow model of muti-fractured horizontal well in dual-porosity formation are established using the theory of seepage flow mechanics, which consider desorption and adsorption, stress sensitive effects and unsteady diffusion effect. Laplace's transformation is used to solve the mathematical model and the curves of pseudo-pressure are drawn in dimensionless coordinate, finally the factors that may influence the curves are analyzed.(4) The real space asymptotic solution of bilinear flow and linear flow phase are obtained by analyzing the characteristics of pseudo-pressure curves, and then the analytical method of linear flow and bilinear flow with regard to pressure data are established.(5) By virtue of the theory research results, the well test analysis software for multi-fractured horizontal well in shale gas reservoir is developed using VC++6.0 in the Windows environment.