Perforation gun with integral debris trap apparatus and method of use

Abstract

The improved perforation gun of the present invention includes an outer gun barrel, which is used in conjunction with an inner movable charge carrier or an inner movable sleeve to trap virtually all of the debris created by the firing of the perforation gun. This elimination of debris reduces costly operational problems in both gravel pack and horizontal well completions. It also improves the production from a perforated underground hydrocarbon bearing formation since there is no debris to potentially cause plugging in the well or subsequent production lines.

1 . A perforation gun assembly comprising:
 an outer gun barrel;   an upper endplate connected to one end of said outer gun barrel;   a lower endplate connected to an end of said outer gun barrel opposite said upper endplate;   a charge carrier slidably mounted inside the outer gun barrel between said upper endplate and said lower endplate, said charge carrier being geometrically similar to the outer gun barrel, said charge carrier having in its interior a plurality of explosive charge receiving areas and said charge carrier having a plurality of pre-drilled holes in the outer wall of said charge carrier, each hole being aligned with a corresponding explosive charge receiving area; and   a stress failing connector holding said charge carrier in place against or near said upper endplate.   
   
   
       2 . The perforation gun assembly of  claim 1  wherein said outer gun barrel has scalloped sections in its outer wall, with each said scalloped section located on said outer gun barrel in an area corresponding to an explosive charge receiving area of said charge carrier. 
   
   
       3 . The perforation gun assembly of  claim 1  wherein an explosive substance is located between said upper endplate and said charge carrier and wherein the perforation gun assembly includes a detonator for said explosive substance. 
   
   
       4 . The perforation gun assembly of  claim 1  wherein said stress failing connector is at least one shear pin. 
   
   
       5 . A method for assembling a perforating gun for capturing the debris created by explosively perforating an underground hydrocarbon bearing formation behind a well casing, said method for assembling comprising the steps of:
 (a) placing explosive charges and a detonator for said explosive charges inside a charge carrier, with each explosive charge being placed in an explosive charge receiving area, and with each explosive charge receiving area being aligned with a corresponding hole in the wall of the charge carrier;   (b) placing the charge carrier inside an outer gun barrel;   (c) affixing the outer gun barrel to an upper endplate and a lower endplate;   (d) affixing the charge carrier to the outer gun barrel in a position located at or near the upper endplate using a stress failing connector; and   (e) positioning the outer gun barrel, upper endplate, lower endplate, explosive charges and charge carrier in a well casing adjacent to an underground hydrocarbon bearing formation.   
   
   
       6 . The method of  claim 5 , comprising the additional step of firing the explosive charges, thereby creating the perforation cavities, causing the inner charge carrier to axially shift along the axis it shares with the outer gun barrel and trap the debris created by the firing of the explosive charges inside the charge carrier.