Patent Grant
7413015
The present invention relates generally to well operations and, more particularly, to a perforating gun.
A perforating gun may be lowered into the well and detonated to pierce a well casing and form fractures in the formation. After the perforating gun detonates, well fluid typically flows into the casing and to the surface of the well via production tubing located inside the well casing.
The present invention provides a system and method of generating one or more perforations in a well casing while simultaneously suppressing burr formation. In one embodiment, the present invention provides a perforating gun capable of being lowered into a well casing. The perforating gun provides a gun housing having an outer surface capable of engaging the inner surface of the well casing. In one embodiment, at least a portion of the outer surface of the gun housing has a diameter substantially equal to the diameter of the inner surface of the well casing.
Through use of an orienting tool, this portion of the gun housing may be positioned to engage the inner surface of the well casing prior to explosive charge detonation. The mass and surface area of the gun housing up against the inner surface of the well casing restricts burr formation both upon the inner surface of the well casing and the outer surface of the gun during explosive charge detonation. In one embodiment, explosive charges are positioned to correspond with the portion of the gun housing designed to engage the inner surface of the well casing.
In another embodiment, the outer surface of the gun housing may be equipped with one or more bow springs. In one embodiment, the outer surface of each bow spring has a diameter substantially equal to the diameter of the inner surface of the well casing. This feature of the present invention allows the bow spring to engage the inner surface of the well casing prior to and during explosive charge detonation. During detonation, the bow spring acts as a sacrificial target and restricts burr formation upon the inner surface of the well casing.
In another embodiment, the present invention provides a sleeve designed for attachment to the outer surface of the gun housing. In one embodiment, the sleeve of the present invention is designed to conform to the inner surface of the well casing. In another embodiment, the sleeve is composed of an inflatable material capable of expanding to engage the inner surface of the well casing prior to and during detonation. Further, the sleeve is capable of retracting to facilitate the removal of the gun housing from the well casing after detonation.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings; it being understood that the drawings contained herein are not necessarily drawn to scale; wherein:
In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
In the specification and appended claims: the terms “connect”, “connection”, “connected”, “in connection with”, and “connecting” are used to mean “in direct connection with” or “in connection with via another element”; and the term “set” is used to mean “one element” or “more than one element”. As used herein, the terms “up” and “down”, “upper” and “lower”, “upwardly” and downwardly”, “upstream” and “downstream”; “above” and “below”; and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments of the invention. However, when applied to equipment and methods for use in wells that are deviated or horizontal, such terms may refer to a left to right, right to left, or other relationship as appropriate.
The invention is herein described as a perforating gun for generating one or more perforations through a well casing and as a method of suppressing burr formation during well casing perforation.
Referring to the Figures, the present invention provides a perforating gun (10) having a gun housing (12). The gun housing contains one or more explosive charges (12E) for use in perforating the well casing (14). The gun housing has a generally cylindrical configuration having inner and outer surfaces (12I and 12O, respectively).
Referring to
The unique configuration of the outer surface of the gun housing allows for greater surface contact between the perforating gun (10) and the inner surface (14I) of the well casing (14) prior to and during detonation of the explosive charges (12E) held within the gun housing.
In one embodiment, the perforating gun of the present invention may be positioned within the well casing such that the explosive charges therein are aligned to detonate in the preferential stress direction (20) for fracturing. The perforating gun may be positioned within the well casing through use of any number of known orienting tools and/or techniques (not shown). Positioning the outer surface of the gun having the unique configuration against the inner surface of the well results in burr suppression during detonation of explosive charges in the preferential stress direction. In short, the mass of the perforating gun and the increased surface contact between the gun and the inner surface of the well casing suppresses burr formation.
Although
Referring to
The unique configuration of the outer surface of the bow spring allows for greater surface contact between the gun housing (10) and the inner surface (14I) of the well casing (14) prior to and during detonation of the explosive charges (12E) held within the gun housing. During detonation, the bow spring acts as a sacrificial target and suppresses burr formation upon the inner surface of the well casing. By suppressing burr formation on the inside of the well casing, the present invention allows other well completion tools, such as packers, to be conveyed past the perforations (18) in the well casing (14) without incurring damage.
In one embodiment, the perforating gun of the present invention may be positioned within the well casing such that the explosive charges therein are aligned to detonate in the preferential stress direction (20) for fracturing. In one embodiment, one bow spring is provided for each direction of explosive charge detonation. For example, if the perforating gun has a 0/180 degree phased arrangement, two bow springs may be utilized. In the case of spiral phasing, a bow spring having a spiral configuration may be utilized.
The perforating gun may be positioned within the well casing through use of any number of known orienting tools and/or techniques. Further, the explosive charges may be aligned/phased to enable the explosive charge to proceed from the gun housing, through the bow spring, and into the well casing.
Although
Referring to
In one embodiment, the purpose of the external sleeve is to centralize the perforating gun so that all explosive detonations are uniform in all directions. Further, the sleeve (22) is capable of providing a sacrificial target such that when the explosive charge penetrates the sleeve, a burr is created on the inside surface (221) of the sleeve (22) instead of upon the inside surface (14I) of the well casing (14).
The sleeve of the present invention is capable of expanding and contracting to the inner surface of the well casing. In one embodiment, the outer surface (22O) of the sleeve conforms to the inner surface of the well casing prior to and during explosive charge detonation in order to suppress burr formation on the inner surface of the well casing. In one embodiment, the sleeve of the present invention comprises a radial spring attached to the outer surface of the gun housing and capable of expanding and retracting according to the inner surface of the well casing during gun insertion and retraction. The radial spring may also be configured to provide one or more bypass slots to accommodate fluid flow through the well casing.
This feature of the present invention allows the perforating gun to be inserted downwardly into the well casing prior to explosive charge detonation, then withdrawn after detonation. By providing a sleeve capable of conforming to the inner surface of the well casing, the goal of suppression burr formation may be achieved.
As with the embodiments described above, the mass of the sleeve and the increased surface contact with the inside surface of the well casing suppresses formation of burrs during detonation. The sleeve may be composed of any material or combination of materials capable of conforming to the inner surface of the well casing and providing sufficient mass to suppress burr formation upon the inner surface of the well casing. The sleeve may be equipped with one or more bypass slots to allow for fluid bypass within the well casing. In one embodiment, bypass slots may be placed between shot planes.
In one embodiment, the sleeve may be filled with a fluid, i.e., a liquid or gaseous substance, to allow for controlled expansion and contraction. In one embodiment, the sleeve provides walls defining one or more cavities (24) capable of receiving fluids. This feature of the present invention allows the sleeve to be smaller than the area provided by the inner surface of the well easing for easy insertion and removal. In one embodiment, the sleeve of the present invention forms an air-tight seal with the outer surface of the gun housing. It understood that the sleeve may be unsealed as well.
Upon reaching the desired depth within the well casing, fluids may then be injected into the sleeve, i.e., as a propellant, causing the sleeve to expand and contact the inner surface of the well casing prior to and during explosive charge detonation. Once expanded, the sleeve acts as a burr suppression tool during detonation. In one embodiment, perforation of the sleeve during detonation causes the sleeve to deflate such that the sleeve may be withdrawn from the well casing. In one embodiment, perforating the sleeve results in an equalization of the internal pressure of the sleeve with internal pressure within the well casing. This feature of the present invention allows the perforating gun and the sleeve to be removed from the well casing after explosive charge detonation.
Although
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.
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| Number | Date | Country | |
|---|---|---|---|
| 20070044968 A1 | Mar 2007 | US |
