Numerical investigation of hydraulic fracture deflection in large-angle oblique horizontal wells with staged multi-cluster fracturing

Abstract

The oblique horizontal well with a large-angle deviated from the direction of the minimum horizontal stress is an essential pilot for stimulating the middle unstimulated area between well pads. It is important to understand the complex deflection behavior of staged multi-cluster hydraulic fractures in oblique horizontal wells. In this study, we develop a fully coupled model of multistage hydraulic fracturing for oblique horizontal wells based on the discrete lattice method, in which synthetic microseismic events are calculated. We quantitatively investigate the effects of horizontal stress difference, injection rate, cluster spacing, and horizontal wellbore azimuth on fracture morphology and fracture deflection, including deflection angle and deflection distance. Simulation results and field microseismic monitoring show that fracturing the oblique horizontal well can stimulate the middle unstimulated area between well pads. Landing the horizontal wellbore in an area with low horizontal stress difference can help improve the stimulation efficiency. Injection rate and cluster spacing have a limited effect on the deflection angle and deflection distance of hydraulic fractures. The horizontal wellbore azimuth, however, significantly affects the fracture morphology and the fracture deflection behavior. Our research results provide theoretical guidance for the optimization and design of efficient fracturing for large-angle oblique horizontal wells.