Impact of perforations on hydraulic fracture tortuosity

We performed scaled model tests to study the relation between completion an d treatment parameters and the near wellbore geometry for highly deviated, cased perforated wellbores. We have instrumented our casings to observe the moment fluid flow around the casing causes a significant increase in the a mount of pressure acting on the wall of the borehole. When fluid flow aroun d the casing occurs extensively before fracture initiation, this leads effe ctively to an open hole situation at the moment of initiation. Otherwise th e perforations will be the only possible initiation sites. In our experimen ts with a perforation phasing of 90 degrees the perforations on top of the borehole acted in most cases as initiation sites. We performed stress calcu lations with a simple analytical model to understand the influence of the p erforation angle on initiation pressure and fracture propagation.