An insert for a high strength polymer-based cartridge casing can include an outside, an inside formed within the insert, and a back end disposed at a rear of the cartridge casing. The back end includes a rim and groove disposed around the outside of the insert and a primer pocket disposed inside the back end. Also included is a front end, opposite the back end, having an overmolded area disposed around the outside of the insert above the primer pocket and a basin, having a depth, formed inside the overmolded area. A flash hole can be included inside the insert and communicating between the primer pocket and the basin. The flash hole has a perimeter and a ring disposed around the perimeter of the flash hole, including a height starting at a bottom of the basin, disposed toward the front end, and less than the depth of the basin.

An insert for a high strength polymer-based cartridge casing can include an outside, an inside formed within the insert, and a back end disposed at a rear of the cartridge casing. The back end includes a rim and groove disposed around the outside of the insert and a primer pocket disposed inside the back end. Also included is a front end, opposite the back end, having an overmolded area disposed around the outside of the insert above the primer pocket and a basin, having a depth, formed inside the overmolded area. A flash hole can be included inside the insert and communicating between the primer pocket and the basin. The flash hole has a perimeter and a ring disposed around the perimeter of the flash hole, including a height starting at a bottom of the basin, disposed toward the front end, and less than the depth of the basin.

A perforating system including a perforating gun having a perforating gun body housing shaped charges oriented outwardly from the gun body and connected to a detonation system for deployment into a wellbore. The shaped charges include at least a case, a liner and explosive material that is thermally stable and of a composition that allows for reaction with metals, debris or formation walls in order to improve fluid flow from the formation upon perforating. Shaped charge can also employ differences in composition moving from the apex to the skirt of the liner in order to achieve different perforating characteristics upon detonation of the explosive material.

The detonation of one or more explosive charges and propellant charges by a detonator in response to a fire control signal from a command and control system comprised of a command center and instrumentation center with a communications link therebetween. The fire control signal is selectively provided to the detonator from the instrumentation center if plural detonation control switches at the command center are in a fire authorization status, and instruments, and one or more interlocks, if included, are in a ready for firing status. The instrumentation and command centers are desirably mobile, such as being respective vehicles.

The detonation of one or more explosive charges and propellant charges by a detonator in response to a fire control signal from a command and control system comprised of a command center and instrumentation center with a communications link therebetween. The fire control signal is selectively provided to the detonator from the instrumentation center if plural detonation control switches at the command center are in a fire authorization status, and instruments, and one or more interlocks, if included, are in a ready for firing status. The instrumentation and command centers are desirably mobile, such as being respective vehicles.

An insert for a high strength polymer-based cartridge casing can include an outside, an inside formed within the insert, and a back end disposed at a rear of the cartridge casing. The back end includes a rim and groove disposed around the outside of the insert and a primer pocket disposed inside the back end. Also included is a front end, opposite the back end, having an overmolded area disposed around the outside of the insert above the primer pocket and a basin, having a depth, formed inside the overmolded area. A flash hole can be included inside the insert and communicating between the primer pocket and the basin. The flash hole has a perimeter and a ring disposed around the perimeter of the flash hole, including a height starting at a bottom of the basin, disposed toward the front end, and less than the depth of the basin.

A line charge includes a thin plastic tube that is deployed by a mechanical means. The thin plastic tube is filled with an explosive material after deployment to form a line charge suitable for route clearance or demolitions.

An explosive system for fracturing an underground geologic formation adjacent to a wellbore can comprise a plurality of explosive units comprising an explosive material contained within the casing, and detonation control modules electrically coupled to the plurality of explosive units and configured to cause a power pulse to be transmitted to at least one detonator of at least one of the plurality of explosive units for detonation of the explosive material. The explosive units are configured to be positioned within a wellbore in spaced apart positions relative to one another along a string with the detonation control modules positioned adjacent to the plurality of explosive units in the wellbore, such that the axial positions of the explosive units relative to the wellbore are at least partially based on geologic properties of the geologic formation adjacent the wellbore.

An insert for a high strength polymer-based cartridge casing can include an outside, an inside formed within the insert, and a back end disposed at a rear of the cartridge casing. The back end includes a rim and groove disposed around the outside of the insert and a primer pocket disposed inside the back end. Also included is a front end, opposite the back end, having an overmolded area disposed around the outside of the insert above the primer pocket and a basin, having a depth, formed inside the overmolded area. A flash hole can be included inside the insert and communicating between the primer pocket and the basin. The flash hole has a perimeter and a ring disposed around the perimeter of the flash hole, including a height starting at a bottom of the basin, disposed toward the front end, and less than the depth of the basin.

An insert for a high strength polymer-based cartridge casing can include an outside, an inside formed within the insert, and a back end disposed at a rear of the cartridge casing. The back end includes a rim and groove disposed around the outside of the insert and a primer pocket disposed inside the back end. Also included is a front end, opposite the back end, having an overmolded area disposed around the outside of the insert above the primer pocket and a basin, having a depth, formed inside the overmolded area. A flash hole can be included inside the insert and communicating between the primer pocket and the basin. The flash hole has a perimeter and a ring disposed around the perimeter of the flash hole, including a height starting at a bottom of the basin, disposed toward the front end, and less than the depth of the basin.