1. Field of Invention
The invention relates generally to the field of oil and gas production. More specifically, the present invention relates to a perforating system. Yet more specifically, the present invention relates to a shaped charge having a modified boss for use in a perforating gun system.
2. Description of Prior Art
Perforating systems are used for the purpose, among others, of making hydraulic communication passages, called perforations, in wellbores drilled through earth formations so that predetermined zones of the earth formations can be hydraulically connected to the wellbore. Perforations are needed because wellbores are typically completed by coaxially inserting a pipe or casing into the wellbore. The casing is retained in the wellbore by pumping cement into the annular space between the wellbore and the casing. The cemented casing is provided in the wellbore for the specific purpose of hydraulically isolating from each other the various earth formations penetrated by the wellbore.
Perforating systems typically comprise one or more perforating guns strung together, these strings of guns can sometimes surpass a thousand feet of perforating length. In
Perforating guns typically include a cylindrical gun strip 16 coaxially housed within a gun body 14. Shaped charges 8 are provided within the gun strip 16 and aimed generally perpendicular to the axis of the wellbore 1.
The shaped charges 8 are typically connected to a detonating cord 27 which is affixed to the shaped charge 8 by a case slot 25 proximate to the booster charge 26. Igniting the detonation cord 27 creates a compressive pressure wave along its length that initiates the booster charge 26 that in turn ignites the high explosive 24. When the high explosive 24 is detonated, the force of the detonation collapses the liner 22 and ejects it from one end of the charge 8 at very high velocity in a pattern called a “jet” 12. The jet 12 perforates the casing and cement lining the wellbore 1 and creates a perforation 10 that extends into the surrounding formation 2.
Shaped charges 8 also include a boss 20 protruding outward from the case 18 perpendicular to the axis ASC of the case 18. The boss 20 fully circumscribes the case 18 outer circumference. A perspective example of the gun strip 16 is provided in
Disclosed herein is a perforating gun with a first shaped charge having a charge case, a liner, and explosive disposed between the liner and charge case. The perforating gun also includes an annular gun strip, a first boss on the charge case partially circumscribing the charge case outer periphery, a first hole formed through the side of the gun strip, and a landing on the gun strip and adjacent the hole formed to mateingly cooperate with the first boss. A second boss may optionally be provided on the charge case partially circumscribing the charge case outer periphery. The respective ends of the first and second boss may, in one embodiment, be substantially equidistant from one another. The lengths of the first and second boss may range from about 10% to about 30% of the charge case circumference. The length of the first and second boss may be about 20%. A second landing may be included on the gun strip and adjacent the hole formed to mateingly cooperate with the second boss. The charge case has an open end and a closed end, and an axis extending through the open and closed ends, the charge case being substantially symmetric about the axis. The gun strip may include a second hole in the gun strip adjacent to the first hole, a web defined by the portion of the gun strip body between the first hole and the second hole, a landing on the gun strip on the second hole perimeter, the landings being disposed away from the web. The web dimensions comprise structural integrity sufficient for a high density perforating gun. The perforating gun may further comprise a detonation cord coaxially extending through the gun strip, and a cord slot formed on the bottom end of the charge case formed for attachment with the detonation cord, the first boss and landing formed to align the cord slot with the detonation cord when inserted into the hole. The landing may comprise notches configured to mate with the respective ends of the first boss and a planar section between the notches.
Also disclosed herein is a method of forming a wellbore perforating device comprising, (a) providing a shaped charge with a first boss that partially circumscribes the shaped charge outer periphery, (b) providing a gun strip with a first hole and a first landing formed adjacent the hole edge, the landing configured to cooperatively mate with the first boss, (c) inserting the shaped charge into the gun strip hole, and (d) cooperatively mating the first boss with the first landing. The shaped charge in the method may further include a second boss partially circumscribing the shaped charge outer periphery and the gun strip may further include a second landing configured to cooperatively mate with the first boss, the method further comprising cooperatively mating the second boss with the second landing. The perforating device may further comprise a second shaped charge having a boss partially circumscribing its outer periphery, a second hole, a landing formed adjacent the second hole configured to cooperatively mate with the boss of the second shaped charge, and a web portion defined between the first and second hole, wherein the landings are disposed away from the web. The web dimensions are sufficient for use in a high density perforating gun application. The method may further comprise deploying the perforating device within a wellbore and initiating detonation of the shaped charges.
Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:
While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. For the convenience in referring to the accompanying figures, directional terms are used for reference and illustration only. For example, the directional terms such as “upper”, “lower”, “above”, “below”, and the like are being used to illustrate a relational location.
It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.
A crown portion 41 defines the portion of the case body 34 extending from the upper terminal end of the upper portion 35. The upper most portion of the crown portion 41 defines the opening of the charge case 32 and lies in a plain that is largely perpendicular to the axis Ax. In the embodiment shown, the crown portion 41 has an outer surface extending generally parallel with the axis Ax. A boss element 38 is provided on the outer surface of the crown portion 41. The boss element 38 is an elongated member whose elongate section partially circumscribes a portion of the outer peripheral radius of the crown portion 41, and thus partially circumscribes the outer circumference of the charge case 32. In the embodiment shown, the boss element 38 cross section is largely rectangular and extends outward from the outer radius of the charge case 32.
Provided in
For the purposes of discussion herein, a high density shot typically has at least 10-12 shaped charges per linear foot of perforating gun. In some instances however high density shots may include guns having as few as 6 shots per linear foot. Referring again to
The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.