CFD simulation of flow interference between multi-stage fractures along a horizontal wellbore

Abstract

This paper investigates flow interference between multiple hydraulic fractures along a horizontal wellbore. The flow interference may cause large production rate losses and is a threat to reservoir asset management, but it has not received sufficient attention. Capable of simulating complex fluid flow phenomena with a high degree of accuracy, Computational fluid dynamics (CFD) simulation is employed to investigate the flow interference behavior of individual fracture streams and bulk flow in a horizontal wellbore with different fracture numbers and spacing and to provide insights into the relationship between fracture number, fracture spacing, flow velocity, pressure differential, and flow interference intensity. The results show that flow interference arises from competition for flow space between fracture streams. A longer horizontal wellbore and more hydraulic fractures can lead to higher bulk flow velocity and thus higher interference intensity. The interference intensity is found to be positively dependent on fracture number with a fixed fracture spacing. The velocity behaviors of individual fracture streams driven by declining pressure differential are also studied, showing a decline trend related to flow velocity. The intensity undergoes a mitigatory process before reaching a steady decline, and even flow interference at a lower intensity level still can lead to large production rate losses and profit reduction. The study suggests the need for countermeasures during well design and fracturing design to mitigate flow interference and reduce asset management risk.