Abstract:
A liner setting tool. A system for conveying a liner string into a subterranean well includes a liner setting tool which selectively connects and disconnects a work string and a liner string. The liner setting tool is configured to transmit compressive force, tensile force and torque between the work string and the liner string. In another system, the liner setting tool is operable to disconnect the work string from the liner string in response to a predetermined pressure differential applied to the liner setting tool. In yet another system, the liner setting tool is operable to disconnect the work string from the liner string in response to displacement of a release member of the liner setting tool followed by displacement of the work string relative to the liner string.

Description:
BACKGROUND  
       [0001]     The present invention relates generally to equipment utilized and operations performed in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides a liner setting system.  
         [0002]     Difficulties are sometimes encountered in conveying liner strings into wells. For example, a wellbore into which a liner string is conveyed may have a restriction (such as, due to a partial cave-in of the wellbore) which makes it difficult to convey the liner string through the wellbore. These problems are especially significant in highly deviated or horizontal wellbores where the liner string rubs against a lower side of the wellbore with the weight of the liner string pressing against the side of the wellbore, and where the weight of a work string used to convey the liner string into the wellbore may not be sufficient to push the liner string through the wellbore.  
         [0003]     It would be helpful to be able to manipulate the liner string in various ways using the work string when such difficulties are encountered. Unfortunately, typical liner setting tools are not able to apply tensile force, compressive force and torque from a work string to a liner string. Thus, typical liner setting tools are hampered by this inability to adequately manipulate a liner string.  
         [0004]     Therefore, it may be seen that improvements are needed in the art of liner setting tools. It will also be appreciated by those skilled in the art that improved liner setting tools should provide convenient and reliable release of a work string from a liner string.  
       SUMMARY  
       [0005]     In carrying out the principles of the present invention, a liner setting system is provided which solves at least one problem in the art. An example is described below in which a liner setting tool is releasably connected to a liner setting sleeve in a manner which permits enhanced manipulation of a liner string by a work string, but which also permits multiple convenient and reliable methods of releasing the liner string from the work string.  
         [0006]     In one aspect of the invention, a system for conveying a liner string into a subterranean well is provided. The system includes a liner setting tool which selectively connects and disconnects a work string and the liner string. The liner setting tool is configured to transmit compressive force, tensile force and torque between the work string and the liner string.  
         [0007]     In another aspect of the invention, a system for conveying a liner string into a subterranean well includes a liner setting tool which is operable to disconnect the work string from the liner string in response to a predetermined pressure differential applied to the liner setting tool. The liner setting tool may also be operable to disconnect the work string from the liner string in response to a predetermined force applied to a release member of the liner setting tool.  
         [0008]     In yet another aspect of the invention, a system for conveying a liner string into a subterranean well includes a liner setting tool which is operable to disconnect the work string from the liner string in response to displacement of a release member of the liner setting tool followed by displacement of the work string relative to the liner string. The relative displacement may be displacement of the work string toward the liner string. These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of a representative embodiment of the invention hereinbelow and the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a schematic partially cross-sectional view of a liner setting system embodying principles of the present invention;  
         [0010]     FIGS.  2 A-C are cross-sectional views of successive axial sections of a liner setting tool which may be used in the system of  FIG. 1 , the tool embodying principles of the present invention;  
         [0011]      FIG. 3  is an enlarged detail of the tool of FIGS.  2 A-C; and  
         [0012]      FIG. 4  is another enlarged detail of the tool of FIGS.  2 A-C. 
     
    
     DETAILED DESCRIPTION  
       [0013]     Representatively illustrated in  FIG. 1  is a system  10  which embodies principles of the present invention. In the following description of the system  10  and other apparatus and methods described herein, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. In the context of operations and equipment in a wellbore, the upper direction is representatively toward the earth&#39;s surface along the wellbore. Additionally, it is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention. The embodiments are described merely as examples of useful applications of the principles of the invention, which is not limited to any specific details of these embodiments.  
         [0014]     As depicted in  FIG. 1 , a work string  12  (such as a string of drill pipe, coiled tubing, etc.) is used to convey a liner string  14  into a wellbore  16 . The wellbore  16  is highly deviated from vertical, and so it is more likely that difficulties will be encountered in conveying the liner string  14  through the wellbore than would be the case if the wellbore were more vertically oriented.  
         [0015]     It should be clearly understood that it is not necessary in keeping with the principles of the invention for a liner string to be conveyed into a horizontal or highly deviated wellbore. This is merely one example of a situation in which the principles of the invention may be applied with beneficial effect.  
         [0016]     As used herein, the term “liner string” is used to indicate any type of tubular string which functions to line a wellbore. A liner string may be comprised of continuous and/or segmented tubular members, metal and/or non-metal materials, and/or any other type of tubular string.  
         [0017]     Referring additionally now to FIGS.  2 A-C, an enlarged cross-sectional view is representatively illustrated of the work string  12  and liner string  14  apart from the remainder of the system  10 . In this view a liner setting tool  20  may be seen which releasably connects the work string  12  and liner string  14 . The tool  20  is connected (for example, by threading) to a lower end of the work string  12 . The tool  20  secures the work string  12  to the liner string  14  in a unique manner described more fully below, while also allowing the work string to be conveniently and reliably disconnected from the liner string when desired (such as, when the liner string has been appropriately positioned in the wellbore  16 ).  
         [0018]     The tool  20  includes an outer liner setting sleeve  22  which is attached at an upper end of the liner string  14 . The sleeve  22  may also be considered as a part of the liner string  14 , since it remains attached at the upper end of the liner string when the remainder of the tool  20  is retrieved with the work string  12  at the end of the liner setting operation. The sleeve  22  provides convenient access for tools, tubing strings, etc., into the liner string  14  by virtue of a muleshoe shaped upper end  24 . Note that it is not necessary for the upper end  24  to have the muleshoe shape.  
         [0019]     The remainder of the tool  20  is engaged with the sleeve  22  (and, thereby, with the liner string  14 ) by means of internal recesses or profiles  26 ,  28  and a splined connection  30 . These forms of engagement permit tensile force, compressive force and torque to be transmitted via the tool  20  between the work string  12  and the liner string  14 , so that the liner string may be manipulated as needed to convey the liner string through the wellbore  16 .  
         [0020]     A tensile force between the work string  12  and the liner string  14  may be considered as a “pull” which tends to separate the work string from the liner string (such as, the weight of the liner string suspended by the work string, or a tensile force resulting from upward displacement of the liner string by the work string, etc.). A compressive force between the work string  12  and the liner string  14  may be considered as a “push” which tends to bias the work string and liner string toward each other (such as, a weight of the work string applied to the liner string, etc.).  
         [0021]     Referring additionally now to  FIG. 3 , an enlarged detail of the tool  20  is illustrated. In this view it may be seen that a C-shaped ring  32  carried on the tool  20  is engaged with the profile  28  in the sleeve  22 . The ring  32  is biased outwardly into engagement with the profile  28  by means of multiple circumferentially distributed balls  34  maintained in an outwardly displaced position by a radially enlarged portion  36  formed on a release member  38 . Note that the balls  34  could instead be pins, lugs, keys, or another type of engagement device.  
         [0022]     If the release member  38  is displaced downward, the balls  34  will be permitted to displace inwardly, thereby permitting the ring  32  to displace inwardly out of engagement with the profile  28 . Note that, as long as the release member  38  is in the position depicted in  FIG. 3 , the engagement between the ring  32  and the profile  28  permits compressive force to be transmitted between the tool  20  and the liner string  14 . However, when the release member  38  is displaced downward, so that the balls  34  are no longer outwardly supported by the portion  36 , then the ring  32  retracts (preferably due to its own elasticity) out of engagement with the profile  28 , and compressive force may no longer be transmitted, due to such disengagement between the ring and the profile.  
         [0023]     Referring additionally now to  FIG. 4 , another enlarged detail of the tool  20  is depicted. In this view it may be seen that another C-shaped ring  40  is carried on the tool  20  and is engaged with the profile  26 . The ring  40  is outwardly supported in engagement with the profile  26  by a housing assembly  42  of the tool  20 .  
         [0024]     Note that a shoulder  44  formed on the housing assembly  42  permits a tensile force to be transmitted between the work string  12  and the liner string  14  due to the engagement between the ring  40  and the profile  26 . However, there is no corresponding shoulder to permit a compressive force to be transmitted. Therefore, engagement between the ring  32  and profile  28  transmits compressive force as described above, and the engagement between the ring  40  and profile  26  transmits tensile force. The benefits of this arrangement will be more fully appreciated after considering the further description of the tool  20  below.  
         [0025]     A radially reduced portion  46  is formed on the housing assembly  42  above the ring  40 . Downward displacement of the housing assembly  42  relative to the sleeve  22  will eventually result in the radially reduced portion  46  being positioned beneath the ring  40 , at which point the housing assembly will no longer outwardly support the ring in engagement with the profile  26 . The ring  40  will consequently retract (preferably due to its own elasticity) out of engagement with the profile  26 .  
         [0026]     The splined connection  30  transmits torque between the housing assembly  42  and the sleeve  22 , and thus between the work string  12  and the liner string  14 . The splined connection  30  also permits relative axial displacement between the housing assembly  42  and the sleeve  22 . This relative axial displacement is used to advantage in the tool  20  when it is desired to disconnect the work string  12  from the liner string  14 .  
         [0027]     The release member  38  is provided in the form of a sleeve which is retained in position relative to the housing assembly  42  by shear pins  48 . A flow passage  50  extends longitudinally through the member  38  and the remainder of the tool  20 . The flow passage  50  permits fluid to be circulated through the work string  12  and liner string  14  while the liner string is conveyed through the wellbore  16 .  
         [0028]     The member  38  may be displaced downward to retract the ring  32  out of engagement with the profile  28  when it is desired to disconnect the work string  12  from the liner string  14 . A predetermined downwardly directed mechanical force may be applied to the member  38  to shear the shear pins  48  and displace the member downwardly. For example, a conventional slickline or wireline conveyed jar could be used for this purpose.  
         [0029]     Alternatively, a plug  52  (such as a ball or dart, etc.) may be dropped and/or pumped through the work string  12  into the passage  50  to engage a seat  54  or other sealing surface on the member  38 . Sealing engagement between the plug  52  and the seat  54  closes off the passage  50  so that pressure applied to the work string  12  will result in a pressure differential being applied to the tool  20 . When the pressure differential reaches a predetermined level across the plug  52  and member  38 , the shear pins  48  will shear and the pressure differential will bias the member to displace downwardly.  
         [0030]     When the member  38  has displaced downwardly a sufficient distance, openings  56  formed through a sidewall of the member, which were formerly sealed off by seals  58 , will no longer be sealed off and will permit flow through the passage  50 , thereby relieving (or at least significantly reducing) the pressure differential across the member. This reduction in the pressure differential can be conveniently detected at the surface as a reduction in pressure on the work string  12 , or as circulating flow to the annulus. Thus, proper actuation of the tool  20  can be easily verified.  
         [0031]     In operation, the tool  20  is connected between the work string  12  and the liner string  14  as depicted in  FIGS. 1 and 2 A-C. If difficulty is encountered in conveying the liner string  14  into or through the wellbore  16 , fluid may be circulated through the work string  12  and liner string via the passage  50 , and the work string may be used to raise, lower and rotate the liner string, to thereby aid in overcoming such difficulty.  
         [0032]     When it is desired to disconnect the work string  12  from the liner string  14 , a pressure differential may be applied from the interior to the exterior of the tool  20  (e.g., by applying increased pressure to the interior passage  50  as a cementing plug lands in a float collar connected at a lower end of the liner string  14 ). This pressure differential will act across a differential piston area on the release member  38  (i.e., the annular area between the seals shown in  FIG. 4  and the seals  58  shown in  FIG. 2C ) to apply a downwardly directed force to the release member. When the pressure differential reaches a predetermined level, the shear pins  48  will shear and thereby permit the release member  38  to displace downwardly.  
         [0033]     If the application of the pressure differential between the interior and exterior of the tool  20  is unsuccessful, then the plug  52  may be dropped and/or circulated into the passage  50  and engaged with the seat  54 . Pressure is then applied to the work string  12  to cause a predetermined pressure differential to shear the shear pins  48  and downwardly displace the member  38 . Such downward displacement of the member  38  will be readily detected at the surface, due to flow being restored through the passage  50 .  
         [0034]     Note that, due to the somewhat restricted flow area of the passage  50  in the release member  38 , a pressure differential in the passage across the release member could be created by flowing fluid through the passage, without installing the plug  52  in the passage. Thus, fluid flow through the passage  50  could be increased until the predetermined pressure differential across the release member  38  is produced, at which point the shear pins  48  would shear and the member would be downwardly displaced by the pressure differential.  
         [0035]     If this pressure actuation of the tool  20  is unsuccessful, then a mechanical force may be applied to the member  38  to shear the shear pins  48  and downwardly displace the member. Again, downward displacement of the member  38  will be detected at the surface. Note that it is not necessary for mechanical actuation to follow an unsuccessful pressure actuation of the tool  20 . For example, the tool  20  could be initially mechanically actuated, if desired.  
         [0036]     Note that an upwardly directed mechanical force could be applied to the member  38  to shear the shear pins  48  and upwardly displace the member, if desired.  
         [0037]     Displacement of the member  38  results in disengagement of the ring  32  from the profile  28 , thereby permitting relative displacement of the work string  12  toward the liner string  14 , since the resulting disengagement between the ring and profile no longer permits transmission of compressive force between the work string and the liner string. However, engagement between the other ring  40  and profile  26  still permits transmission of tensile force between the work string  12  and the liner string  14 , and the splined connection  30  still permits transmission of torque between the work string and the liner string.  
         [0038]     The work string  12  is then displaced toward the liner string  14  (for example, by lowering the work string). This results in downward displacement of the housing assembly  42  relative to the sleeve  22 . When the housing assembly  42  displaces downward sufficiently far, the ring  40  will disengage from the profile  26 . At this point, neither tensile nor compressive force will be transmitted between the work string  12  and liner string  14 , although the splined connection  30  will still transmit torque between the work string and liner string.  
         [0039]     The work string  12  is then retrieved from the well with the tool  20  (with the exception of the sleeve  22  which remains attached to the liner string  14 ). The splined connection  30  is disengaged as the housing assembly  42  is withdrawn from within the sleeve  22 .  
         [0040]     It may now be fully appreciated that the tool  20  permits the liner string  14  to be disconnected from the work string  12  by conveniently pressure actuating the tool (which may be readily verified), displacing the work string toward the liner string, and then retrieving the work string. The tool  20  can be mechanically actuated if desired, whether or not an attempt is also made to pressure actuate the tool.  
         [0041]     Of course, a person skilled in the art would, upon a careful consideration of the above description of a representative embodiment of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the described embodiment, and such changes are within the scope of the principles of the present invention. For example, the rings  32 ,  40  and profiles  26 ,  28  could be replaced by pins, lugs, dogs, keys, recesses, shoulders, projections, or any other type of engagement mechanisms. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.