Conventional perforating systems exhibit a distribution of perforation entry hole diameters around the circumference of the casing, when the system is decentralized within the wellbore. In the case of horizontal, limited entry, cluster style perforating operations the perforating system normally lies along the bottom of the casing. When hydraulically fracturing these intervals, perforation efficiency is difficult to predict since the entry hole diameters and perforation penetrations are not definitive.
A perforating system has been developed which provides a consistent entrance hole diameter and formation penetration independent of the clearance between the perforating carrier and casing. The system has been engineered to provide optimal perforation placement and to ensure that every perforation is the same regardless of circumferential position. The system provides a somewhat shallower penetration depth than conventional charges but some data suggests that depth of penetration may not significantly impact unconventional fracturing operations.
The system has been field tested in well over 5000 stages in a variety of unconventional resource field applications. Direct comparisons with conventional perforating systems show improved perforation efficiency as observed through step rate test analysis conducted during hydraulic fracturing operations.
Case studies are presented which illustrate the impact of having all perforations with a consistent penetration and constant entry hole diameter. With each individual perforation configured identically, no one perforation can dominate during hydraulic fracturing operations, and as a result more perforations may contribute to fracture development.