What is Hollow Carrier Gun System?

A hollow carrier gun system is a pressure-tight carrier made from steel tubing. The inside of the carrier houses all energetic components, such as shaped charges and detonating cord as well as all necessary mechanical support structures. The interior of the hollow carrier gun remains at atmospheric conditions with none of the internal components being exposed to the well bore pressure or fluid keeping most of the debris after initiation inside the carrier. Hollow carrier guns are typically used by all types of conveyors, in all well conditions, natural completions, stimulated completions (unconventional wells) or sand control completions. 

Hollow carrier gun is typically described by the outer diameter (OD), shot density in shots per foot (SPF) or shots per meter (SPM), shaped charge types and the pressure & temperature rating - depending on explosive types used. In addition to the shot density, we also define hollow carriers by the phasing of charges being loaded in relation to the preceding and subsequent charges. The carrier guns typically come in two varieties: slick or scalloped.  

Each hollow carrier perforating gun system consists of the following:

? Carrier (4) incl. end caps (6)

? Loading Tube (1) incl. endplates (2) & optional centralizer (7)

? Snap / retaining ring (5)

The length of hollow carrier guns that can be run is only limited by the tensile strength of the carrier itself, adapters (subs) used, conveyance methods as well as the well profile. 

All hollow carrier gun systems swell when being shot and must survive the forces of the charge detonations without cracking, splitting or swelling too much. The swell will ensure the customer is able to retrieve the spent gun system safely and without getting stuck (see previous article on Hollow Carrier Gun Survival).

 Many parameters and factors affect the maximum swell and survivability of a hollow carrier gun system. There is no hard and fast rule of which gun size can be safely deployed into any giving well bore as it depends on the customers personal preference, well bore environment, fishing contingencies, well bore ID (drift ID + Casing Burr) or profiles to name a few.

Generally speaking a nipple profile as min ID can usually have a smaller clearance than a continuous min ID inside tubing or casing. If the customer is in doubt about min clearance or if to run a certain gun system or not, a drift with a previously shot (spent) gun of the same type and load can be recommended.

Hollow carrier gun systems are categorized into two major groups:

 ? Liquid gun systems are those where the fluid around the gun (in the casing) has a density of water (1.0g/cc) or greater. These guns are qualified in engineering testing with the gun carrier covered in fluid at ambient pressure.

? Gas gun systems are those that may be shot in a fluid or gas. These guns are qualified in engineering testing with the gun carrier in air at ambient pressure.

The following graphic will give a general indication of which hollow Carrier gun system can be run in any given casing or tubing, keeping in mind the well bore environment (liquid or gas), the casing drift ID, Casing Burr, fishing contingencies, gun swell and any other possible restrictions.

All Hollow carrier guns are single-use and need to be disposed of after initiation and retrieval from the well. 

Currently, DynaEnergetics hollow carrier guns range from 1-9/16 inches to 7 inches in outer diameter with a shot density of up to 18 spf or 59 spm with many phasing options including oriented. 

For more information, visit DynaEnergetics.com.