Patent Publication Number: US-2011073325-A1

Title: Torque resistant coupling for oilwell toolstring

Description:
TECHNICAL FIELD 
     The present application relates generally to a toolstring for use in downhole oilwell operations, and more specifically to designs for connecting parts of a toolstring such as adapters for a gauge device, a propellant device and/or perforating guns that are resistant to unlocking/unscrewing torque to each other or a carrier such as a wireline or a coiled tubing. 
     BACKGROUND 
     There are desirable fluids located underground such as water and hydrocarbons. To reach and extract those fluids a well is drilled into the earth. These activities can occur subsea, i.e., below the ocean and into the ocean floor. 
     Once the well is drilled, a metal casing is often placed within the wellbore. That casing can be cemented in place. Normally the casing is perforated in order to connect the interior of the wellbore with the formation where the desirable fluids are located. The fluids access the interior of the wellbore via the perforations and are then extracted. 
     Perforations are generally created by a perforating gun. A perforating gun is a tubular device having a number of shaped charges that fire in a generally radial direction through the casing, cement, and into the formation, thereby creating perforations in the casing and cement, and tunnels into the formation. 
     A typical shaped charge has a metal jacket or a charge case. High explosive material is disposed inside the metal jacket. A liner retains the explosive material in the jacket during the period prior to detonation. A primer column provides a detonating link between a detonating cord and the explosive. 
     When the shaped charge is detonated a portion of the liner forms a jet portion. The jet is propelled away from the jacket in a direction toward a target. Another portion of the liner is propelled away from the jacket and forms what is known as a slug or carrot portion of the liner. The slug or carrot portion is not propelled to the same extent as the “jet”. When the shaped charge is used in a perforating gun, the target is normally a cased downhole formation. Upon detonation, the jet portion of the liner is propelled through the casing and penetrates the downhole formation to enhance recovery of downhole hydrocarbons. The slug portion, on the other hand, is designed to break up upon contact with the casing. 
     Oftentimes a large length of wellbore requires perforating. However, the length of most perforating guns is not sufficient for one gun to perforate the required length of wellbore casing. Therefore a number of guns are frequently connected to one another, e.g., by adapters having threaded connections. 
     Also, after perforating and related to production, a gauge and/or other tools are lowered on a toolstring. Also, fracturing activities require fracturing guns to be lowered on a toolstring. In addition, other devices often are lowered and connected in a toolstring via an adapter/housing arrangement. 
     In connection with those activities, adapters can be used to connect the various devices with the toolstring, a carrier (e.g., wireline, coiled tubing or production tubing) and/or with one another depending on the setup of the toolstring. 
     The various tools are often connected by way of adapters/housing having a threaded connection. 
     Accordingly, there exists a need to ensure that the threaded connection does not become compromised and unscrew in downhole operations. 
     SUMMARY 
     Embodiments in the present application relate to a downhole oilwell toolstring having an adapter having a male threaded portion, a longitudinally extending tubular female housing having a female threaded portion on an inner surface of the housing, a first end a second end, and a recessed groove extending around the circumference of the interior surface of the female housing at a location between the first end and the female threaded portion. The adapter has a first end and a second end, and a recessed groove extending around the outer circumference of the adapter at a location between the threaded portion and the first end of the adapter. The female housing is connected with the male adapter by way of the female threaded portion and the male threaded portion engaging one another. A ring is located in the recessed groove in the adapter and the recessed groove in the female housing. 
     Other or alternative embodiments having fewer or additional features will be apparent from the following description, from the drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain embodiments will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and: 
         FIG. 1  is a cross sectional view of a portion of an embodiment; 
         FIG. 2  is a cross sectional view of a portion of the design shown in  FIG. 1 ; 
         FIG. 3  is a cross sectional view of a portion of an embodiment; and 
         FIG. 4  is a cross sectional view of a portion of an embodiment. 
     
    
    
     It is to be noted, however, that the appended drawings illustrate embodiments and are therefore not unduly limit any present or subsequent related claims. 
     DETAILED DESCRIPTION 
     In the following description, numerous details are set forth to provide an understanding of the various embodiments. However, it will be understood by those skilled in the art that those embodiments presented may be practiced without many of those details and that numerous variations or modifications from the described embodiments may be possible. These embodiments are not meant to unduly limit the scope of any present or subsequent related claims. 
     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. 
     Lock screws are typically used to keep items in a toolstring, e.g., perforating guns and other equipment, from accidentally becoming unscrewed downhole. Screws, although well proven in use, have several issues in the manufacturing process such as drilling and tapping screw holes in the adapter, holes in the housing or gun holes, and potential lost parts on the rig floor. Other issues include the time and tediousness of installation. 
     According to the present application, a resistant torque ring or lock ring can be used to keep mating members from unscrewing by using an internal bevel to collapse the ring and later an internal groove to allow the ring to expand in and resist torque by limiting movement in an axial direction. 
     To aid in removal, an additional internal bevel can be used to collapse the ring while unscrewing the adapter separating it from the housing. If increased removal torque is required, the internal bevel can be reduce or removed to the point where the ring is sheared to release. 
     Locking of housings or guns with adapters is a concern for the field due to the potential issue of them coming unscrewed downhole. One method/design to reduce or eliminate this unscrewing potential, which also reduces manufacturing cost, is to use a ring shaped device to resist rotation and/or axial movement of a housing mated to an adapter. 
     A groove with a ring can be placed on the male portion of the adapter with threads beyond the sealing area and the female housing can have an internal groove to lock in the ring beyond the sealing area of the thread. When the housing and adapter are screwed together, the ring will collapse and spring into the groove of the housing when screwed in far enough. This type of anti-rotation ring reduces or eliminates the need for screws on the rig floor for locking the adapter together. Also, manufacturing cost is reduced by eliminating the need for screw holes, holes in the housing, and/or the cost of the screws. 
     Another type of anti-rotation device may not have a collapsible ring but have the outer housing thin enough to expand and trap a machined ring integrated with the adapter. The machined ring could instead merely be a raised portion. 
     Along the lines noted above,  FIG. 1  shows a side section view of a downhole toolstring connecting device  1  including a housing  2  and an adapter  3 . The housing  2  has a female threaded portion  4  on the internal surface of the housing. The female threaded portion  4  mates with a male threaded portion  7  on the external surface of the adapter  3 . 
       FIG. 2  shows a close-up section view of an anti-rotation ring  6  that is located in a recessed groove  5  in the adapter  3  and a recessed groove  8  in the housing  2 . The recessed groove  5  has a generally semi-circular cross section. The anti-rotation ring  6  can be a complete circular ring, or an incomplete ring only substantially forming a circular shape, i.e., with a gap. The recessed groove  5  in the adapter extends around the circumference of the adapter  3  and is generally circular in shape. In the case of an incomplete ring  6 , the groove  5  does not need to extend fully around the circumference. The cross section of the groove  5  could be other shapes, e.g., rectangular or oval. Also, the groove  5  could have a beveled edge. 
     The recessed groove  8  in the housing  2  extends about the circumference of the internal surface of the housing  2 . The groove  8  is shown as having a generally semi-circular profile, but could be oval or rectangular. Also, the groove  8  can have a beveled edge to aid in the insertion and extraction of the anti-rotation ring  6  from the groove  8 . 
     The process of attachment of the housing  2  to the adapter  3  involves placing the housing  2  in a female position with regard to the adapter  3 . The female threaded portion  7  engages the male threaded portion  4  and the parts are rotated with respect to one another thereby advancing the housing  2  and the adapter  3  axially toward one another. As the housing  2  and the adapter  3  advance axially toward one another by rotation, a portion of the housing  2  that is adjacent to the female threaded portion  7  encounters the anti-rotation ring  6 . The force of the hosing  2  compresses the anti-rotation ring  6  into the groove  5  so that the housing  2  can pass over the ring  6 . Once the groove  8  in the housing  2  is properly positioned over the ring  6 , the ring  6  expands and moves into position within the groove  8 . At that point, the ring  6  applies axial force to the hosing  2  in opposition to axial movement of the housing  2  with respect to the ring  6  and/or the adapter  3 , thereby discouraging unscrewing (or further screwing) of the threaded connection. 
       FIG. 3  shows a design where the ring  6  has a rectangular profile. Also, the housing  2  has an angular surface  9  connecting with a flat surface at an end of the housing  2 . A similar angular surface  10  is adjacent to the groove  8  in the housing and can be adapted to aid in extraction of the ring  6  from the groove  8 . 
       FIG. 4  shows an alternate design where instead of a ring located within a groove, a raised portion  11  is formed on the external surface of the adapter  3  in a similar location as the groove  5  and the ring  6  would otherwise be located. In contrast, with this design the housing  2  is configured in such a manner, i.e., with such a thickness, that the housing can be forced over and onto the raised portion  11  so that the raised portion  11  interlocks with the groove  8  in the housing, thereby providing resistance to movement in the axial direction and therefore to rotation and unscrewing. A bevel similar to that (bevel  9 ) in  FIG. 3  may be included to aid in passage of the housing  2  over the raised portion  11 . 
     Although only a few embodiments have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this application. Such modifications are intended to be included within the scope as defined in the claims.