Abstract:
A well tool locking apparatus compatible with high temperature, high pressure well conditions comprises a packing ring mandrel that carries a sliding locking dog cage. The locking dogs are expanded radially into a tubing nipple channel by the axial translation of a ramped step on the mandrel surface. Chevron ring packing seals are positioned between the locking dog cage and an abutment shoulder around the mandrel. Translation of the mandrel against the locking dog cage engages the tool locking dogs and expands the chevron ring seal against the inside bore surface of the tubing nipple. The locked and sealed position is held by buttress threads on the mandrel engaged with a body lock ring

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application claims the priority of U.S. Provisional application serial No. 60/413,037 filed Sep. 24, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to tools for developing and producing fluids from subterranean wells. More particularly, the invention is a wireline or coiled tube positioned locking apparatus for securing the position of a production tube flow control or measurement tool in a landing nipple located in a tubing string having a profile and seal bore specifically prepared to accept the locking apparatus with packing.  
           [0004]    2. Description of Related Art  
           [0005]    A prior art procedure for placing and securing a subterranean well tool at a predetermined position within a well production tube is a special purpose locking apparatus having a collet or locking dogs that are mechanically actuated by surface manipulated wirelines or coiled tubing. Usually, the locking tool is attached to the top of the well tool or instrument and to a wireline running tool. The assembly is lowered into the well at the end of the wireline to the desired depth and location. Radially expandable locking dogs or collets are actuated, for example, by wireline manipulation to engage or mesh with cooperative surfaces, receptacles or profiles within the tubing.  
           [0006]    A common method of positioning a subterranean well tool within a well conduit, such as a tubing string, is to insert a locking apparatus in a landing nipple, the landing nipple being pre-installed at a particular location within the tubing string and containing a profile into which the locking apparatus may engage. The locking apparatus will normally no-go on a shoulder of the landing nipple and will have means of locking into the profile of the landing nipple using outward expanding members such as dogs or collets.  
           [0007]    Normally associated with the locking apparatus is a set of chevron packing rings to provide a seal between the landing nipple and a well tool attached to the locking apparatus, such as a blanking plug or safety valve. Typically, the packing is positioned in a polished seal bore of the landing nipple, between two fixed limiting shoulders on the locking apparatus and a well tool such as a blanking plug or safety valve. Unfortunately, however, it is not unusual for the seal bores of the landing nipple to be damaged in the well either by wireline cutting (longitudinal grooves) or by general corrosion. Prior art locking devices have not provided a mechanism or procedure to apply axial compressive loading of the packing to improve sealing by extrusion into such grooves pits or imperfections.  
           [0008]    U.S. Pat. No. 4,295,528, for example, is a patent for a “Selective Lock with Setting and Retrieving Tools.” Element  104  in FIG. 2 c  of this &#39;528 patent represents a chevron packing unit or assembly installed on the mandrel of the wireline lock in a typical manner. The purpose of the chevron packing is to provide a seal between the mandrel and the seal bore in a landing nipple. However, the chevron packing material is only confined between two fixed shoulders at each end of the packing and has no capacity for operational adjustment.  
           [0009]    Similar fixed or static shoulder confinements for chevron seals are disclosed in U.S. Pat. Nos. 4,315,544; 4,510,995; 4,583,591; and 4,823,872. U.S. Pat. Nos. 4,406,324 and 4,993,493 also disclose oilfield equipment that employs chevron packing located between two fixed shoulders. The chevron packing is landed either on the lock mandrel or the tool attached to the lock mandrel and is always trapped between two fixed shoulders that position and confine the chevron packing rings but does not compress them.  
           [0010]    Somewhat different in concept is the locking device described in U.S. Pat. No. 5,348,087 which can actually have a seal bore larger than the internal diameter of the tubing string. The locking device contains an elastomeric packing element located on a mandrel. The mandrel contains an enlarged diameter portion which, when driven beneath the packing element, causes the packing element to expand radially and engage the seal bore of the nipple. Due to relative movement of the mandrel, the expanding metal rings on each side of the packing element can not be considered fixed until after the lock is set. After the lock is set, however, they essentially become fixed with respect to the packing element and there is no provision for applying or increasing the end load on the packing element of this device as a means for improving the sealing.  
           [0011]    It is, therefore, an object of the present invention is to provide a locking apparatus having the ability to apply axial compressive loading on a chevron packing or other packing configuration associated with the locking apparatus.  
           [0012]    Another object of the present invention is a means to improve the sealing ability of locking apparatus packing under adverse condition such as mechanical or chemical corrosion damage to seal the bore of the landing nipple or other adverse sealing condition such as high pressure and high temperature.  
           [0013]    Also an object of the present invention to provide a locking apparatus having the ability to apply an axial compressive load to the chevron packing to improve sealing of the packing using conventional wireline manipulation means.  
           [0014]    Another object of the present invention is locking apparatus mechanism having the capacity to apply an axial end load to the chevron seal packing thereby forcing the packing material into grooves or other imperfection in the seal bore of the landing nipple to effect a seal when otherwise, the seals would leak.  
           [0015]    Also an object of the invention is provision of an ability to apply an axial compressive load to locking apparatus chevron seals to aid in sealing the tubing bore under high pressure, high temperature applications, even when the seal bore in the landing nipple is perfect.  
           [0016]    An additional object of the invention is to provide the means of applying additional axial compressive loading in a remedial action to shut off an existing leak using normal wireline manipulation means.  
         SUMMARY OF THE INVENTION  
         [0017]    The invention provides an ability to apply a compressive, axial loading on the chevron packing to expand the packing material radially thereby forcing the chevron packing material into the grooves, pits or other imperfections in the seal bore of the landing nipple and thereby effecting a seal when otherwise, the seal would leak.  
           [0018]    To these ends, the present well tool locking connector includes an interior packing mandrel having a first cylindrical surface that carries a compression expanded packing ring that is axially confined along the packing mandrel first surface by an compression abutment shoulder. An axial extension of the packing mandrel transitions over a ramped shoulder onto a second, lesser diameter cylindrical surface. At least a portion of the second cylindrical surface extended from the ramped shoulder is profiled with directionally biased channels such as buttress threads. A body lock ring having a correspondingly profiled I.D. meshes with the packing mandrel surface profile.  
           [0019]    Further along the packing mandrel extension from the ramped shoulder and the meshed locking ring is a fishing tool connection surface such as a locking dog receptacle detent or channel or a fishing barb ring.  
           [0020]    Between the fishing tool connection surface and the meshed locking ring, a control sleeve slidably overlies the packing mandrel extension. The control sleeve also includes a fishing tool connection surface such as that used for the packing mandrel, preferably. Distal from the fishing tool connection, the control sleeve includes an abutment shoulder band having an O.D. shoulder in facing proximity with the fishing tool connection and an I.D. shoulder in facing proximity with the locking ring. The I.D. shoulder of the control sleeve is axially recessed from a retaining ring abutment shoulder.  
           [0021]    A locking dog caging sleeve slidably overlaps the first cylindrical surface of the packing mandrel and the control sleeve abutment shoulder band. An end of the caging sleeve lapped upon the first cylindrical surface of the packing mandrel proximate of the packing ring is a compression ram. An opposite distal end of the caging sleeve includes a I.D. abutment shoulder in facing proximity with the O.D. abutment shoulder of the control sleeve. One or more locking dogs are confined by caging slots in the caging sleeve. A radially expandable retaining ring provides a preset connection between the body lock ring and the caging ring.  
           [0022]    A preset alignment of the tool components is secured by calibrated shear fasteners. Such preset alignment provides a retracted position for the locking dog or dogs and an uncompressed packing ring for well run-in. When suspended at the end of a suitable suspension structure such as a wireline or coiled tubing, for location within a well, the fishing tool engagement surfaces respective to the packing ring mandrel and the control sleeve are axially separated by a first manipulation of the suspension structure to translate the packing ring mandrel relative to the caging sleeve and the control sleeve. This translation draws the ramped shoulder of the mandrel under or in radial contiguity with the locking dog thereby causing a radial displacement of the locking dog or dogs into a well tubing receptacle or detent channel. Simultaneously, the packing ring is compressed between the mandrel compression shoulder and the ram end of the caging sleeve. Such compression expands the sleeve radially to a pressure sealing engagement with the inside bore wall of the well tube.  
           [0023]    When the packing mandrel is drawn against the control sleeve, the buttress threads are translated under the lock body ring to rectify the movement and secure the compressed position.  
           [0024]    At this point, the tool connector is locked and sealed with the tubing bore. The suspension structure may be released from the fishing tool connection surfaces and withdrawn from the well for replacement by other tools, if desired.  
           [0025]    When release of the well tool from the tubing is desired, fishing tools reengage the mandrel and control sleeve. A second manipulation of the suspension structure translates the control sleeve from abutted engagement of the respectively facing abutment surfaces. This translation of the control sleeve also extracts a spacing hood portion of the control sleeve from between the retaining ring and the caging sleeve thereby permitting it to expand out of linkage engagement between the lock ring and the caging sleeve. A third manipulation of suspension structure translates the first cylindrical surface of the mandrel from under the locking dog or dogs thereby permitting a radial retraction of the dog from the tubing channel. The same mandrel translation decompresses the packing ring.  
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0026]    For a thorough understanding of the present invention, reference is made to the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawing.  
         [0027]    [0027]FIG. 1 is a sectioned view of a locking apparatus in operative assembly with a running tool set for well run-in.  
         [0028]    [0028]FIG. 2 is a sectioned view of a locking apparatus in operative assembly with a running tool in an intermediate well setting condition.  
         [0029]    [0029]FIG. 3 is a sectioned view of a locking apparatus in operative assembly with a running tool in a set and sealed condition within a well production tube.  
         [0030]    [0030]FIG. 4 is a sectioned view of a locking apparatus in operative assembly with a running tool where the locking apparatus is in a set and sealed condition and the running tool is released from the locking apparatus.  
         [0031]    [0031]FIG. 5 is an enlarged sectioned view of the locking apparatus configured for well run-in.  
         [0032]    [0032]FIG. 6 is an enlarged sectioned view of the locking apparatus configured for a locked and sealed setting within a well production tube.  
         [0033]    [0033]FIG. 7 is an enlarged sectioned view of the locking apparatus configured for release from a well production tube.  
         [0034]    [0034]FIG. 8 is an enlarged sectioned view of the packing seal portion of the locking apparatus.  
         [0035]    [0035]FIG. 9 is an enlarged sectioned view of an alternative packing seal assembly.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0036]    A first embodiment of the invention is represented by FIG. 1 to include a running tool  10  attached to a wireline lock  20 . The running tool  10  comprises An inner mandrel  12  that may be a threaded assembly of several sections to provide a structurally continuous tube element that extends between a threaded box end  13  and a threaded pin end  14 . Optionally, the pin end may also include a fishing neck  15 . A running tool housing  30  is releasably secured to the mandrel  12  by a calibrated failure element such as a shear pin  32 . The housing  30  is secured to the mandrel  12  at such a position as to provide translational space  62  between the sleeve end  35  and a mandrel abutment shoulder  64 . The translational space  62  is covered by a housing extension sleeve  36 . Opposite from the extension sleeve  36 , the housing further includes a control dog housing  66 . The control dog housing has a control dog detent channel  37  for cooperation with a control dog element  38 . Additionally, the control dog housing provides a multiplicity of caging slots  41  for fishing neck dogs  40 .  
         [0037]    When free of the locking dog  38 , the control dog housing  66  may slidably translate along a spring mandrel  16 . A compression spring  17  is seated between the shoulder  68  on the control dog housing  66  and the spring seat shoulder  18  on the spring mandrel  16 . The bias of spring  17  is to separate the respective spring seats and translate the spring mandrel end  70  into the space  72 .  
         [0038]    The outside perimeter of the inner mandrel  12  is profiled to provide a locking dog retraction channel  75  on one side of a locking dog support band  77  and a ramped shoulder  79  on the other side.  
         [0039]    The inside perimeter of the spring mandrel  16  is profiled to provide a ramped shoulder  80  to cooperatively engage the ramped shoulder  79  on the inner mandrel  12 . The outside perimeter of the spring mandrel  16  is also profiled with a ramped shoulder  82  for cooperative engagement with a corresponding inside shoulder ramp  90  near the end of the control dog housing  66 .  
         [0040]    Respective to FIGS. 1 and 5, the primary structural element of the locking apparatus  20  is the packing mandrel  22  which includes the mandrel sleeve extension  25 . The packing mandrel directly supports a chevron packing  28  against a compression shoulder  84 . One or more shear pins  34  releasably secure the packing mandrel  22  to the running tool spring mandrel  16 . Box threads  27  secure the locking apparatus to additional elements of the tool assembly that are to be secured within the production tube. The inside perimeter of the packing mandrel sleeve extension  25  accommodates a fishing tool connection channel  44 .  
         [0041]    With respect to FIG. 5, the outer profile of the mandrel sleeve extension  25  is stepped to provide an elongated groove channel between an abrupt shoulder  86  and a ramped shoulder  88  on the packing mandrel  22 . Between the shoulders  86  and  88 , the outside surface of the ring channel is grooved by, for example, buttress threads or rings  48 . A lock ring  56  has corresponding buttress threads around its inside circumference to mesh with the threads  48 . The lock ring  56  is an expansible hoop spring that will accommodate radial expansion to advance axially in one direction over the buttress threads  48  but opposes movement in the opposite axial direction.  
         [0042]    A control sleeve  46  is slidably confined within the groove extension channel between the abrupt shoulder  86  and the lock ring  56 . The end of the control sleeve proximate of the abrupt shoulder  86  has a threaded connection with a lock assembly sleeve  23  whereby both elements function dynamically as an integral structure.  
         [0043]    The control sleeve  46  also includes a hood extension  49  that projects over the lock ring  56 . The hood extension  49  includes a counterbored shoulder that confines a retainer ring  58  against an end shoulder of a locking dog cage  52 . The retainer ring  58  is an expansible hoop spring that is biased to expand against the inside surface of the hood extension  49 .  
         [0044]    An extension  54  of the locking dog cage  52  laps over the control sleeve  46  and the hood extension  49 . The distal end of the cage extension  54  is rimmed to provide an outside abutment face  55  and an inside abutment shoulder  57 . The locking dog cage  52  laps onto the outside packer seal surface of the packer mandrel  22  to cover a translational space  59  between the ramped shoulder  88  of the of the mandrel  22  and the lock ring  56 . Within the locking dog cage  52  are a plurality of locking dogs  50  that are confined by slots to radial movement into and out of the translational space  59 . A corresponding translational space  96  is provided between the inside abutment shoulder  57  and a control sleeve shoulder  47 . A calibrated failure fastener  60  such as a shear screw secures an initial axial relationship between the locking dog cage  52  and the control sleeve  46 . A safety fastener  24  between the lock assembly sleeve  23  and the packing mandrel sleeve  25  also provides alignment security during transport to the well location. The safety fastener  24  is removed, however, after the locking apparatus  20  is assembled to the running tool but before it is inserted in the well.  
         [0045]    Preparatory to well descent, the wireline lock tool  20  is assembled with the running tool  10  in the manner illustrated by FIG. 1. The inner mandrel  12  of the running tool is secured to the sleeve  35  end of the housing  30  by the upper shear pin  32 . An end thread on the mandrel  12  secures it to a tool joint pin  14  to facilitate connection of the assembly to a well suspension structure such as a wireline or coiled tubing.  
         [0046]    The spring mandrel  16  is aligned along the inner mandrel  12  length to position the locking dog support band  77  under the control dog  38  thereby meshing the control dog  38  into the detent ring  37  in the control dog housing  66 . This meshing of the control dog  38  in the housing  66  detent ring  37  immobilizes the spring mandrel  16  with the housing  30  and hence, due to the upper shear pin  32 , with the inner mandrel  12 .  
         [0047]    The lower end of the running tool  10  penetrates the central bore of the locking apparatus  20  to receive the lower shear pin  34  through the spring mandrel  16 . This calibrated shear failure assembly is supplemented by the meshed engagement of the fishing neck dog  40  with the detent channel  42  in the lock assembly sleeve  23 . The meshed engagement of the fishing neck dog  40  is supported by the outside surface of the spring mandrel  16 .  
         [0048]    Before the assembly enters the wellhead, the safety fastener  24  is removed. The locking apparatus  20  remains mechanically linked to the running tool  10  by the fishing neck dog  40  and the lower shear pin  34 .  
         [0049]    Upon alignment with the desired downhole location, the assembly is “jarred” to shear the upper shear pin  32 . That event allows the running tool housing  30  to translate along the inner mandrel  12  and close the translational space  62  as illustrated by FIG. 2. This axial downward shifting of the inner mandrel  12  with respect to the housing  30  also translates the control dog support land  77  downward out from underneath the control dogs  38  allowing the control dogs  38  to drop into the locking dog retraction channel  75 . Alignment of the control dog  38  with the retraction channel  75  allows the control dog  38  to be radially displaced within the control dog cage of the spring mandrel  16  and out of the detent channel  37  in the control dog housing  66 .  
         [0050]    Retraction of the control dogs  38  from the control dog housing  66  releases the spring mandrel  16  relative to the housing  30  but does not release the spring mandrel from the packing mandrel  22  of the locking apparatus  20  due to the lower shear pin  34 . Support linkage is also maintained by the fishing neck dog  40  engagement with the detent channel  42  in the lock assembly sleeve  23  and the abutment of shoulders  82  and  90  on the spring sleeve and control dog housing, respectively.  
         [0051]    Furthermore, the control dog housing  66  is biased downward against the lock assembly sleeve  23  while the spring mandrel  16 , connected by lower shear pin  34  to the packing mandrel  22 , is biased upward, both due to the urging of the compression spring  17 . Consequently, when the control dogs  38  are released from the control dog housing  66 , the upward bias of the spring mandrel  16  lifts the packing mandrel  22  while holding the lock assembly sleeve  23  down thereby causing a compressive closure between the packing mandrel  22  and the locking dog cage  52  shown by FIG. 3. As the ramped shoulder  88  of the packing mandrel  22  engages with the locking dogs  50 , the locking dogs are radially displaced into a dog receptacle channel  102  in the landing nipple  100  component of the well fluid production tube thereby securing the locking apparatus  20  to the landing nipple  100  by a mechanical interference as is illustrated by FIGS. 3 and 4.  
         [0052]    Continued expansion of the spring  17  by compression of the packing ring  28  displaces the spring mandrel  16  relative to the control dog housing  66  until the support land  92  portion of the spring mandrel  16  passes from under the fishing neck dog  40 . As the ramped shoulder  82  passes the fishing neck dog  40  (FIG. 6), the dog  40  drops from the detent channel  42  thereby releasing the running tool  10  from the locking apparatus at that point. However, the shear pin connection  34  between the spring mandrel  16  and the packing mandrel  22  remains.  
         [0053]    With the locking apparatus thus secured to the landing nipple, additional upward jarring movement of the inner mandrel  12  as shown by FIG. 4 causes the upward facing bevel at the lower end of the control dog retraction channel  75  to engage the inner bevel of the control dogs  38 . With the inner mandrel  12  in physical abutment with the control dogs  38 , such subsequent upward jarring shears the lower shear pin  34  to complete the release of the running tool  10  from the locking apparatus  20 . Before the running tool release sequence is complete, however, the process imposes maximum compressive load against the chevron packing ring  28  between the ram end  53  of the locking dog cage  52  and the compression shoulder  84  of the mandrel  22 . When compressed axially, the packing ring expands radially out to a pressure sealed engagement with the landing nipple I.D.  104 . Upon shear failure of the pin  34 , the running tool  10  is released from the locking apparatus  20  and may be removed from the well.  
         [0054]    Also before the release sequence is complete, as the packing mandrel  22  is drawn against the relatively fixed position of the locking dogs  50  and cage  52 , the sleeve  25  also advances the buttress threads  48  on the outer surface of the packing mandrel sleeve  25  under the lock ring  56 . FIG. 6. As long as the retainer ring  58  remains engaged with the lock ring  56 , displacement of the packing mandrel  22  relative to the locking dog cage  52  and control sleeve  46  is unidirectional. The buttress thread bias between the mandrel threads  48  and lock ring  56  prevents a reverse movement. Hence, the locking dogs  50  and packer seal  28  are secured at the engagement position with the landing nipple  100 .  
         [0055]    Displacement of the packing mandrel sleeve  25  relative to the control sleeve  46  also opens a translational space  87  shown by FIG. 6 between the abrupt shoulder  86  on the packing mandrel sleeve  25  and the stepped end of the control sleeve  46 . This translational space  87  will come into use for eventual retrieval of the locking apparatus  20   
         [0056]    Retrieval of the locking tool may be accomplished by a fishing tool not illustrated but of construction and operation as is well known to the prior art. In particular, such fishing tools have two or more sets of axially translated fishing dogs carried by either a wireline or continuous tube workstring. Such fishing dogs are of common use in the industry.  
         [0057]    Applied to the present invention, one set of such fishing dogs is manipulated to engage the outer detent channel  42  in the lock assembly sleeve  23 . An inner fishing dog set engages the inner detent channel  44  in the packing mandrel sleeve  25 . The lock assembly sleeve  23  has a threaded connection to the control sleeve  46  and when translated by force exerted by the outer fishing dog set on the outer detent channel  42 , the screw  60  that links lock assembly sleeve  25  to the packing mandrel sleeve  25  fails and the control sleeve shoulder  47  is shifted against the inside abutment shoulder  57  on the end of the cage extension  54 .  
         [0058]    Translation of the control sleeve  46  withdraws the radial structure support of the hood extension  49  from the retainer ring  58  as shown by FIG. 7. Consequently, the retainer ring expands against the inside diameter of the cage extension  54 . When expanded, the retainer ring  58  no longer links the locking dog cage  52  to the lock ring  56  and the packing mandrel sleeve  25 . Hence, the packing mandrel sleeve  25  may be shifted by force applied with inner fishing dogs to the inner detent channel  44 . This packing mandrel shift is oriented toward axial separation of the compression shoulder  84  from the ram end  53  of the locking dog cage  52 . Hence, the seal surface  26  supporting the locking dogs  50  engagement with the landing nipple  100  is withdrawn and the locking dogs  50  are radially free to contract against the O.D. surface of the packing mandrel  22 . Consequently, the locking apparatus  20  is released from mechanical interference engagement with the landing nipple  100  and may be withdrawn from the well.  
         [0059]    [0059]FIG. 8 is a close-up view, depicting in greater detail the packing sleeve  28  of the locking apparatus  20 . As shown, the packing sleeve  28  includes a pair of metal end rings  110 ,  112  at either axial end, and a central metal ring  114 . A stack of elastomeric chevron rings  116 ,  118  is disposed axially between each of the end rings  110 ,  112  and the central ring  114 . Each of the chevron rings  116 ,  118  has a peaked, generally V-shaped cross-section that is apparent from FIG. 8. When the ram end  53  compresses the packing sleeve  28 , the chevron rings  116 ,  118  are flattened out such that the peaked V in their cross-section is substantially removed.  
         [0060]    [0060]FIG. 9 is an enlarged cross-sectional view of portions of locking device  20  incorporating an alternative axially compressible seal assembly  120  for use as packing sleeve  28 . The compressible seal assembly  120  is known commercially as a “Dynamic Seal Assembly” available from Baker Hughes Incorporated. As the structure and function of this seal assembly is well known, it will not be described here. Other suitable seal assemblies may also be utilized as or within the packing sleeve  28  in accordance with the present invention, including seal assemblies that incorporate, for instance, axially compressible hat rings and/or U-cups.  
         [0061]    The preferred invention embodiment has been described to function with expanding dog fishing tools to engage the detent channels  42  and  44 . Those of skill in the art will understand that external fishing connectors that accept and connect with overshot fishing tools may obviously be substituted for the internal connectors  42  and  44 .  
         [0062]    Although the invention has been described in terms of particular embodiments which are set forth in detail, it should be understood that this is by illustration only and that the invention is not necessarily limited thereto. Alternative embodiments and operating techniques will become apparent to those of ordinary skill in the art in view of the present disclosure. Accordingly, modifications of the invention are contemplated which may be made without departing from the spirit of the claimed invention.