Abstract

Fixed plane perforation technology is regarded as a good mean to address near wellbore tortuosity and reduce breakdown pressure in low permeability reservoirs. To better understand of the fracture behavior in wellbore perforations at the defining plane, a 2D finite element model has been implemented in ABAQUS to investigate the effects of mechanical, perforation and treatment parameters on hydraulic fracture propagation path. The global zero thickness cohesive elements have been inserted into numerical model, thus the existence of natural fractures on patterns of fracture propagation can be considered in this model. It shows that there is a great impact of natural fracture on the fracture propagation path. Moreover, the fracturing fluid viscosity, pumping rate, in-situ stress and perforation parameters also play critical roles on fracture propagation. Comparisons of numerical simulations show that the effects of the stress anisotropy, pumping rate, fluid viscosity, Young's modulus, Poisson's ratio and perforation intersection angle on the hydraulic fracture geometry of exterior fractures and interior fracture at the defining plane are different. It found that the width of interior fracture is almost zero at the near wellbore zone at the end of pumping which induced by the stress interference of neighboring fractures in some cases, thus perforations design at the defining plane must be carefully considered. Additionally, in most cases, hydraulic fractures from exterior perforations tend to propagate upward and downward simultaneously. Although hydraulic fractures initiated from a perforation that misaligned with the direction along the maximum in-situ stress initially at short distance, hydraulic fractures would finally reorient itself to the maximum in-situ stress direction, thus increase chances of creating one simple transverse fracture along maximum in-situ stress orientation. Because the strong stress interference of competing fractures, the possible breakdown of casing and perforation tunnels should be considered before well completion. The simulation results from this study offer some insights to enhance fixed plane perforation design for hydraulic fracturing treatments.

You can access this article if you purchase or spend a download.