Abstract: A re-fracturing method using a perforating gun system in a multistring wellbore casing with an inner well casing installed in an outer well casing. The charges in the perforating system include a case, a liner positioned within the case, and an explosive filled within the liner. The liner shaped with a subtended angle about an apex of the liner such that a jet formed with the explosive creates an entrance hole in the inner well casing and the outer well casing; the liner having an exterior surface, the exterior surface substantially conical proximate the apex; the subtended angle of the liner ranges from 100° to 120°. The method includes covering the existing openings with the inner casing, perforating with the perforating system and creating constant diameter entrance holes in the outer casing and fracturing through the inner casing and outer casing.

Abstract: A re-fracturing method using a perforating gun system in a multistring wellbore casing with an inner well casing installed in an outer well casing. The charges in the perforating system includes include a case, a liner positioned within the case, and an explosive filled within the liner. The liner shaped with a subtended angle about an apex of the liner such that a jet formed with the explosive creates an entrance hole in the inner well casing and the outer well casing; the liner having an exterior surface, the exterior surface substantially conical proximate the apex; the subtended angle of the liner ranges from 100° to 120°. The method includes covering the existing openings with the inner casing, perforating with the perforating system and creating constant diameter entrance holes in the outer casing and fracturing through the inner casing and outer casing.