PERFORATION GUN WITH INTEGRAL DEBRIS TRAP APPARATUS AND METHOD OF USE
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.
This application is a divisional of co-pending U.S. patent application Ser. No. 11/372,883 filed Mar. 10, 2006, which claims the benefit of and priority to U.S. Provisional Patent Application No. 60/681,553 filed May 16, 2005, the technical disclosure of which is hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION1. Technical Field of the Invention
The present invention relates generally to perforation guns that are used in the oil and gas industry to explosively perforate well casing and underground hydrocarbon bearing formations, and more particularly to an improved method and an improved apparatus for explosively perforating a well casing and its surrounding underground hydrocarbon bearing formation while limiting the amount of explosion debris in the well bore and hydrocarbon bearing formation following perforation.
2. Description of the Related Art
During the completion of an oil and/or gas well, it is common to perforate the hydrocarbon containing formation with explosive charges to allow inflow of hydrocarbons to the well bore. These charges are loaded in a perforation gun and are typically shaped charges that produce an explosive formed penetrating jet in a chosen direction.
While perforation guns do increase fluid production from hydrocarbon bearing formations, the effectiveness of traditional perforation guns is limited by the fact that the firing of a perforation gun can leave behind “debris” inside the casing and the hydrocarbon bearing formation 12. This debris can cause significant operational difficulties for the well operator and has to be cleaned out of the well at a significant cost.
Prior art has proposed an apparatus used to trap this debris before it enters the well casing and hydrocarbon bearing formation, which is disclosed in Rospek et. al. PCT Application WO 2005/033472.
A need exists for an improved and more comprehensive and more efficient design for a debris trapping perforation gun. A further need exists for an improved, more comprehensive and more efficient method of operation of the debris trapping perforation gun.
SUMMARY OF THE INVENTIONThe present invention is thus directed to an improved perforation gun, which traps debris created by the explosion inside the gun. One embodiment overcomes many of the disadvantages of the Rospek '472 prior art by pre-drilling holes in the interior charge carrier. The holes in the charge carrier allow the explosive charges to easily pass through the charge carrier. This reduces or eliminates the damage done to the charge carrier by the explosive charges, which in turn allows the charge carrier to shift inside the gun with less resistance than the charge carrier in the Rospek '472 device. This also prevents reduced shaped charge performance as would happen in the Rospek '472 device.
The present invention is also an improvement over the Rospek '472 prior art through another embodiment, which seals the holes in the outer gun barrel using a movable inner sleeve. The inner sleeve has pre-drilled holes and shifts to close the holes created in the outer gun barrel by the explosive charges while holding the charge carrier portion of the gun in place. The shifting inner sleeve with pre-drilled holes also moves with less resistance and more success than the charge carrier in Rospek '472.
A more complete understanding of the method and apparatus of the present invention may be had by reference to the following detailed description when taken in conjunction with the accompanying drawings, wherein:
Where used in the various figures of the drawing, the same numerals designate the same or similar parts. Furthermore, when the terms “top,” “bottom,” “first,” “second,” “upper,” “lower,” “height,” “width,” “length,” “end,” “side,” “horizontal,” “vertical,” and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawing and are utilized only to facilitate describing the invention.
All figures are drawn for ease of explanation of the basic teachings of the present invention only; the extensions of the figures with respect to number, position, relationship, and dimensions of the parts to form the preferred embodiment will be explained or will be within the skill of the art after the following teachings of the present invention have been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following teachings of the present invention have been read and understood.
DETAILED DESCRIPTION OF THE INVENTIONThe present invention involves an improved debris trapping perforation gun and the unique charge carrier or inner sleeve it incorporates. The invention produces superior debris trapping results because the pre-drilled holes in the charge carrier or inner sleeve, as appropriate, limits or eliminates deformations caused by the explosive charges which allows the charge carrier or inner sleeve to shift with more ease and success.
Referring initially to
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In the first preferred embodiment, referring to
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In the second preferred embodiment, referring to
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It should be understood by one skilled in the art that in order for the present invention to be used in practice, explosive charges 16 must be placed in the explosive charge receiving areas 16B before the perforation gun is placed into the well bore. Explosive charges used in the industry vary widely and it is understood by one skilled in the art that a plurality of different explosive charges is within the scope of the present invention.
Even though the figures described above have depicted all of the explosive charge receiving areas as having uniform size, it is understood by those skilled in the art that, depending on the specific application, it may be desirable to have different sized explosive charges in the perforation gun. Also, even though the above described figures have depicted a uniform axial distance between each of the explosive charge receiving areas, it is understood by those skilled in the art that, depending on the specific application, it may be desirable to have varied axial spacing between the explosive charges.
It is also understood by those skilled in the art that several variations can be made in the foregoing without departing from the scope of the invention. For example, the particular number and location of the explosive charges can be varied within the scope of the invention. Also, the particular techniques that can be used to fire the explosive charges within the scope of the invention are conventional in the industry and understood by those skilled in the art.
It will now be evident to those skilled in the art that there has been described herein an improved perforation gun that reduces the amount of debris left in the well bore and perforations in the hydrocarbon bearing formation after the perforation gun is fired.
Although the invention hereof has been described by way of preferred embodiments, it will be evident that other adaptations and modifications can be employed without departing from the spirit and scope thereof. The terms and expressions employed herein have been used as terms of description and not of limitation; and thus, there is no intent of excluding equivalents, but on the contrary it is intended to cover any and all equivalents that may be employed without departing from the spirit and scope of the invention.
Claims
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.
Type: Application
Filed: Aug 15, 2008
Publication Date: Dec 4, 2008
Inventors: Kevin George (Cleburne, TX), Nathan Clark (Mansfield, TX), James Rollins (Fort Worth, TX), David S. Wesson (Fort Worth, TX)
Application Number: 12/192,345
International Classification: E21B 43/116 (20060101);