Effect of Formation Stress Distribution on Hydraulic Fracture Reorientation in Tight Gas Sands

Abstract

Abstract Initial period of production from a fracture stimulated tight gas sands can alter stress distribution around the hydraulic fracture. This allows a new fracture to reorient along a different azimuth, even up to 90 degrees, thereby providing access to less depleted zones and retrieving productivity. Success of hydraulic fracture re-stimulation significantly depends on the stress state of the wellbore adjacent area. Using a finite element based fully coupled poroelastic numerical model which includes wellbore, poroelastic formation, a pair of finite conductive fracture and refracture, this paper examines the effect of production induced stress perturbation on the initiation and orientation of a secondary fracture in hydraulically fractured tight gas reservoirs. Results of this study have shown that the area of stress reorientation around a producing hydraulically fractured well is constrained by two distinct planes. By simulating wellbore re-pressurization, it has been also shown that such stress distribution, which is induced by initial production period, can lead to further propagation of the primary hydraulic fracture instead of reorientation of hydraulic fracture. Furthermore, it has been also observed that properly oriented perforation prior to refracture treatment and/or existence of micro-fractures at the wellbore wall can facilitate refracture reorientation before the primary hydraulic fracture starts propagating.