SPE Production & Facilities · 1999 · 67 citations · 7 references
EngineeringGeological EngineeringPetroleum EngineeringHydraulic FracturingHydraulicsSubsurface Fluid FlowFracture CharacterizationFracture GeometryFracture InitiationFracture PropagationNear-wellbore EffectsWellbore HydraulicsFracture Initiation PressureFracture Propagation ModelingInitiationInitiation PressurePerforation Initiation PressurePerforation PhasingScaled Model TestingTreatment Parameters
Fluid flow around the casing before fracture initiation can create an open‑hole condition, otherwise perforations become the sole initiation sites. We conducted scaled model tests and stress calculations, instrumenting casings to observe how fluid flow increases wall pressure and how perforation angle affects initiation pressure and fracture propagation in highly deviated, cased perforated wellbores. With a 90° perforation phasing, perforations on the borehole top most often served as fracture initiation sites.
Summary We performed scaled model tests to study the relation between completion and 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 signi®cant increase in the amount of pressure acting on the wall of the borehole. When fluid flow around the casing occurs extensively before fracture initiation, this leads effectively to an open hole situation at the moment of initiation. Otherwise the perforations will be the only possible initiation sites. In our experiments with a perforation phasing of 90° the perforations on top of the borehole acted in most cases as initiation sites. We performed stress calculations with a simple analytical model to understand the influence of the perforation angle on initiation pressure and fracture propagation.
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Oriented Perforations - A Rock Mechanics View
Hazim Abass, David Meadows, J. L. Brumley et al. · SPE Annual Technical Conference and Exhibition · 1994 · 115 citations