A semi-analytical model for pressure transient analysis of hydraulic reorientation fracture in an anisotropic reservoir

Abstract

Fracture reorientation can be used to increase well production in an anisotropic reservoir. The principal focus of this work is on the transient pressure analysis for a hydraulic reorientation fracture in a rectangular anisotropic reservoir. By employing the nodal analysis technique, a set of diffusivity equations are developed to describe the flow in a hydraulic reorientation fracture. Then, a semi-analytical solution is obtained by coupling the point source solution and the discrete fracture solution. The validation of this work is demonstrated by comparing the previous study and the numerical simulation for a reorientation fracture. Five typical flow regimes can be observed on this model's transient response. Flux along the reorientation fracture is also generated to analyze the flux distribution at different time. Furthermore, type curves are obtained to investigate the effect of the key parameters on the transient flow behavior, including principal fracture angle, reoriented fracture angle, permeability anisotropy, fracture conductivity and fracture length ratio. For a rectangular anisotropic reservoir, the influence of principal fracture angle, permeability anisotropy and fracture conductivity on the type curves is concentrated in the early-time and middle-time periods, and reoriented fracture angle and fracture length ratio mainly affect the formation linear flow regime.