Patent Application
20050173118
The present invention relates generally to perforating tools used in downhole applications, and more particularly to a holding device for supporting charges in a perforating gun for use in a wellbore.
After a well has been drilled and casing has been cemented in the well, one or more sections of the casing, which are adjacent to formation zones, may be perforated to allow fluid from the formation zones to flow into the well for production to the surface or to allow injection fluids to be applied into the formation zones. A perforating gun string may be lowered into the well to a desired depth and the guns fired to create openings in the casing and to extend perforations into the surrounding formation. Production fluids in the perforated formation can then flow through the perforations and the casing openings into the wellbore.
Typically, perforating guns (which include gun carriers and shaped charges mounted on or in the gun carriers) are lowered through tubing or other pipes to the desired well interval. Shaped charges carried in a perforating gun are often phased to fire in multiple directions around the circumference of the wellbore. When fired, shaped charges create perforating jets that form holes in surrounding casing as well as extend perforations into the surrounding formation.
Various types of perforating guns exist. One type of perforating gun includes capsule shaped charges that are mounted on a strip in various patterns. The capsule shaped charges are protected from the harsh wellbore environment by individual containers or capsules. Another type of perforating gun includes non-capsule shaped charges, which are loaded into a sealed carrier for protection. Such perforating guns are sometimes also referred to as hollow carrier guns. The non-capsule shaped charges of such hollow carrier guns may be mounted in a loading tube that is contained inside the carrier, with each shaped charge connected to a detonating cord. When activated, a detonation wave is initiated in the detonating cord to fire the shaped charges. In a hollow-carrier gun, charges shoot through the carrier into the surrounding casing formation.
The difficulty with conventional hollow carrier guns is that conventional loading tubes are designed to receive only one particular size of shaped charge. Accordingly, if a perforation plan calls for using shaped charges of non-standard sizes (e.g., small shaped charges in a large gun), then a standard or universal loading tube cannot be used and a specialized loading tube must be fabricated.
There exists, therefore, a need for an adapter to facilitate using shaped charges of various sizes in a standard or universal loading tube. The present invention is directed at providing such an adapter.
In general, according to one embodiment, the present invention provides an adapter for mounting a shaped charge having any selected size into a standard or universal loading tube.
For example, an adapter in accordance with one embodiment of the present invention may include a charge holder having an interior bore shaped to receive a small shaped charge and an exterior housing shaped to fit the openings in a universal loading tube, which is generally designed to receive larger charges.
In another example, an adapter may include a charge jacket having a set of support ribs formed on the interior of the jacket to hold a small shaped charge and a latching mechanism for engaging the openings in a universal loading tube, which is set in a larger gun and is thus generally designed to receive larger charges.
Other or alternative features will be apparent from the following description, from the drawings, and from the claims.
The manner in which these objectives and other desirable characteristics can be obtained is explained in the following description and attached drawings in which:
It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
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 described 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.
Referring to
To detonate the shaped charge 10, a detonation wave traveling through the detonating cord 15 initiates the primer column 14 when the detonation wave passes by, which in turn initiates detonation of the main explosive charge 16 to create a detonation wave that sweeps through the shaped charge 10. The liner 20 collapses under the detonation force of the main explosive charge 16. Material from the collapsed liner 20 forms a perforating jet that shoots through the front of the shaped charge 10, as indicated by the arrow 26.
Referring to
Referring to
Generally, once assembled, the gun string 50 is positioned in a wellbore 60 that is lined with casing 62. A tubing or pipe 64 extends inside the casing 62 to provide a conduit for well fluids to wellhead equipment (not shown). A portion of the wellbore 60 is isolated by packers 66 set between the exterior of the tubing 64 and the interior of the casing 62. The perforating gun string 50 may be lowered through the tubing or pipe 64 on a carrier line 70 (e.g., wireline, slickline, or coiled tubing). Once positioned at a desired wellbore interval where the gun string 50 is fired to create perforations in the surrounding casing and formation.
The resulting perforation achieved by detonating these guns may be a function of the physical size and geometrical arrangement of the shaped charges in the loading tube. For example, in the embodiments illustrated in
In another example, the physical size of the shaped charge may dictate the effectiveness of the perforation. Depending on wellbore conditions encountered and perforation results sought, it may be necessary to vary the size of the shaped charges used to achieve a particular result. For instance, smaller (non-standard) shaped charges may be needed to load into a perforating gun having a standard loading tube with openings sized to receive larger charges. Accordingly, an adapter for holding such shaped charges in a standard or universal loading tube is desirable.
The present invention is directed at an adaptor for fitting relatively small shaped charges into a standard loading tube that is designed to receive larger shaped charges. A standard loading tube may generally be a stock item or one that is commonly kept in inventory for use in typical perforating operations. Such a loading tube is generally equipped with a jacket mechanism for receiving shaped charges of a particular shape and size, and is not compatible with receiving shaped charges of a size outside the design parameter.
Generally, one embodiment of the present invention includes an adaptor for holding a shaped charge, wherein the adaptor is connectable to a standard or universal loading tube, and wherein the shaped charge has a shape and size that otherwise would be incompatible with the standard or universal loading tube. The adaptor includes: (1) a mechanism for holding the shaped charge, and (2) a mechanism for mounting the shaped charge to a loading tube.
More specifically, with respect to
In downhole perforation operations, it may be desirable to load a small shaped charge 10 into a hollow carrier gun 30 having a standard loading tube 40. For example, with reference to
In another embodiment, with reference to
While the shaped charge holder 100 illustrated in
Moreover, in another embodiment of the adaptor, the housing assembly 100 is formed to be a single, integrated housing unit (i.e., a single-piece housing instead of a two-piece housing). In this embodiment, the opening in the housing is used to receive the shaped charge.
With respect to
Furthermore, an embodiment of the jacket 300 includes a set of support ribs 302, 304 for supporting a small shaped charge 10 in a position such that the upper surface 10A of the charge is sufficiently close to the carrier 30 and perforating target (e.g., formation production zone) to achieve the desired penetration. The set of ribs includes one or more lower ribs 302 for supporting the bottom of the shaped charge 10 and one or more dorsal ribs 304 for supporting the sides of the shaped charge.
Still furthermore, an embodiment of the jacket 300 includes a small opening 305 and a groove 306 formed in the lower end beneath the axial bore for receiving a detonating cord (not shown). The detonating cord 15 must be held in contact with the primer column 14 of the shaped charge 10 (as shown in
In downhole perforation operations, it may be desirable to load a small shaped charge 10 into a large hollow carrier gun 30 having a standard loading tube 40. For example, with reference to
While various embodiments of the present invention have been described herein with reference to particular size and measurement data, it is intended that the adaptor of the present invention may be used with components (e.g., shaped charges, jackets, loading tubes, and/or hollow carriers) of any size.
Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention.
