Patent Publication Number: US-11643893-B2

Title: Well tool anchor and associated methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a division of prior application Ser. No. 15/699,592 filed on 8 Sep. 2017. The entire disclosure of this prior application is incorporated herein by this reference. 
    
    
     BACKGROUND 
     This disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in one example described below, more particularly provides an anchor and associated methods for securing a well tool and a bottom hole assembly in a well. 
     An anchor can be used to secure a well tool in a desired position in a well. In some situations, the anchor may be required to maintain the well tool or a portion thereof motionless (at least in a longitudinal direction) while a well operation is performed with the well tool (such as, milling, cutting, punching, perforating, etc.). 
     Therefore, it will be appreciated that improvements are continually needed in the art of constructing and utilizing well tool anchors. Such improvements may be useful in a variety of different well operations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a representative partially cross-sectional view of an example of a well system and associated method which can embody principles of this disclosure. 
         FIGS.  2 A  &amp; B are representative cross-sectional views of successive axial sections of an example of an anchor that may be used in the well system and method of  FIG.  1   , and which can embody the principles of this disclosure. 
         FIGS.  3 A-C  are representative cross-sectional views of actuator, grip member and contingency release sections of the anchor in a run-in configuration. 
         FIG.  3 D  is a side view of an alignment device of the grip member section, viewed from line  3 D- 3 D of  FIG.  3 B . 
         FIGS.  4 A-C  are representative cross-sectional views of the actuator, grip member and contingency release sections of the anchor in a set configuration. 
         FIG.  5    is a representative side view of a portion of the grip member section in the set configuration. 
         FIG.  6    is a representative cross-sectional view of the grip member section, taken along line  6 - 6  of  FIG.  5   . 
         FIG.  7    is a representative cross-sectional view of the grip member and contingency release sections in a contingency released configuration. 
     
    
    
     DETAILED DESCRIPTION 
     Representatively illustrated in  FIG.  1    is a system  10  for use with a subterranean well, and an associated method, which can embody principles of this disclosure. However, it should be clearly understood that the system  10  and method are merely one example of an application of the principles of this disclosure in practice, and a wide variety of other examples are possible. Therefore, the scope of this disclosure is not limited at all to the details of the system  10  and method described herein and/or depicted in the drawings. 
     In the  FIG.  1    example, a tubular string  12  is positioned within casing  14  and cement  16  lining a generally vertical wellbore  18 . In other examples, the wellbore  18  may not be lined with casing  14  or cement, and the wellbore  18  may be generally horizontal or otherwise inclined from vertical. 
     The tubular string  12  may be of the type known to those skilled in the art as production tubing, or it may be another type of pipe, conduit, casing, liner or tubing. Any type of tubular string may be used in the system  10 , in keeping with the scope of this disclosure. 
     In the method depicted in  FIG.  1   , it is desired to cut the tubular string  12 , so that an upper portion of the tubular string can be retrieved to surface. The tubular string  12  may need to be severed because a lower section of the tubular string has become stuck in the wellbore  18  (due to, for example, accumulation of debris in an annulus  20  between the casing  14  and the tubular string, collapse of the casing against the tubular string, failure to unset a packer connected in the tubular string, etc.). However, the scope of this disclosure is not limited to any particular purpose for performing a well operation using the method. 
     In order to cut through the tubular string  12 , a bottom hole assembly (BHA)  22  is conveyed into the tubular string  12  and positioned in a location at which it is desired to cut the tubular string. The BHA  22  is “bottom hole” in that it is connected at or near a distal or downhole end of a conveyance  34  with which it is deployed into the wellbore  18 . It is not necessary for the BHA  22  to be positioned at or near a “bottom” of the wellbore  18  or other hole. 
     In the  FIG.  1    example, the BHA  22  includes at least a well tool  24  and an anchor  26  for securing the well tool in the tubular string  12 . The BHA  22  can include a variety of other components and well tools (such as, collar locators and other types of logging or locating devices, adapter subs, valves, motors, centralizers, etc.), and different combinations of components may be used to perform corresponding different well operations. Therefore, the scope of this disclosure is not limited to use of any particular components or well tools, or to any particular combination of components or well tools, in the BHA  22 . 
     The well tool  24  in the  FIG.  1    example comprises a conventional tubing cutter. The well tool  24  is provided with one or more cutters  28  that can be operated to cut through a wall of the tubular string  12 . In various examples, the cutters  28  may be hydraulically, electrically or otherwise powered. 
     Note that it is not necessary for the well tool  24  to be a tubing cutter. The well tool  24  could instead comprise a mill, a puncher or a perforator if respective milling, punching or perforating operations are to be performed. Thus, the scope of this disclosure is not limited to any particular type of well tool included in the BHA  24 . 
     It also is not necessary for the well operation to be performed specifically on the tubular string  12 . In some examples, the well operation may be performed on the casing  14 , cement  16  or other structure in the well. As one example, a structure might be blocking flow or access through the casing  14  or the tubular string  12 , and the BHA  24  may be deployed into the casing or tubular string, in order to mill or drill through the structure. 
     In the  FIG.  1    example, the BHA  22  is deployed into the tubular string  12  with the conveyance  34 , which comprises a coiled tubing string. The tubing string is “coiled” in that it is substantially continuous and is typically stored on a spool or reel at the surface. However, in other examples, other types of tubing strings, whether or not continuous, and other types of conveyances may be used, in keeping with the scope of this disclosure. 
     The anchor  26  depicted in  FIG.  1    includes grip members  30  that grippingly engage an interior surface  32  of the tubular string  12 . The grip members  30  in this example are of the type known to those skilled in the art as “slips” having teeth that bite into the interior surface  32 . In other examples, the grip members  30  may otherwise grip the interior surface  32 , and the grip members may have friction-enhancing or gripping profiles other than teeth for engaging the tubular string  12 . Thus, the scope of this disclosure is not limited to any particular configuration or structure for the grip members  30 . 
     Note that, in the  FIG.  1    example, the grip members  30  engage the interior surface  32  at a same longitudinal position along the tubular string  12 . This can enhance a stability of the BHA  22  as the well operation is performed. 
     As depicted in  FIG.  1   , a restriction  36  is positioned in the tubular string  12  between the surface and the location at which it is desired to cut the tubular string  12 . As a result, the BHA  22  is displaced through the restriction  36  when it is deployed to the cutting location. Thus, the anchor  26  must be small enough to pass through the restriction  36 , and must be capable of extending the grip members  30  outward sufficiently far to engage the interior surface  32  of the tubular string  12 . 
     An example of the anchor  26  is described below in which the anchor has a capability of extending the grip members  30  outward a relatively large distance, from a relatively compact run-in configuration, so that the anchor is capable of passing through a relatively small restriction and then being set in a tubular string below the restriction. However, it is not necessary for the anchor  26  to pass through the restriction  36 , or for the anchor to be capable of extending the grip members  30  any particular distance, in keeping with the scope of this disclosure. 
     In the  FIG.  1    example, the anchor  26  is set by flowing a fluid  38  through the anchor at or above a certain flow rate, in order to extend the grip members  30 . A tensile force Tis then applied to the BHA  22  via the conveyance  34  to increasingly bias the grip members  30  outwardly against the interior surface  32 . The grip members  30 , thus, grippingly engage the tubular string  12  and prevent at least longitudinal displacement of the well tool  24  relative to the tubular string. The grip members  30  may also prevent rotational displacement of the well tool  24  relative to the tubular string  12  (or other interior surface), depending, for example, on a configuration of the grip members. 
     In other examples, the anchor  26  may be set using other techniques in addition to, or in substitution for, flowing the fluid  38  through the anchor and applying the tensile force T to the anchor. In some examples, the anchor  26  may prevent lateral, radial, rotational or combinations of displacements relative to the tubular string  12  or other structure in the well. 
     Note that, when the tensile force T is applied to the anchor  26 , and the grip members  30  are grippingly engaged with the interior surface  32  of the tubular string  12 , the tensile force is transmitted via this gripping engagement to the tubular string. In the  FIG.  1    example, this tensile force Tis advantageously applied to the tubular string  12  at the location in which the tubular string is to be cut. 
     Thus, when the cutters  28  are cutting through the tubular string  12 , the tensile force T prevents the upper portion of the tubular string from bearing down on the cutters, causing the cutters to bind, or otherwise damaging the cutters or other portions of the well tool  24 . However, it is not necessary in keeping with the scope of this disclosure for the tensile force T to be applied to the tubular string  12  in a location where the tubular string is cut. 
     Referring additionally now to  FIGS.  2 A  &amp; B, cross-sectional views of an example of the anchor  26  is representatively illustrated. The anchor  26  is described below as it may be used in the system  10  and method of  FIG.  1   . However, the anchor  26  of  FIGS.  2 A  &amp; B may be used with other systems and methods, in keeping with the scope of this disclosure. 
     For clarity, only the conveyance  34 , the anchor  26  and the well tool  24  are depicted in  FIGS.  2 A  &amp; B. Note that, in this example, the anchor  26  is connected between the well tool  24  and the conveyance  34 . In this manner, the anchor  26  can be used to apply the tensile force T to the tubular string  12  while the well tool  24  is used to cut through the tubular string. 
     In other examples, the well tool  24  could be connected between the conveyance  34  and the anchor  26 , the anchor and/or well tool could be connected between different sections of the conveyance  34 , etc. Thus, the scope of this disclosure is not limited to any particular position, location, relative arrangement or configuration of the anchor  26 , the well tool  24  or the conveyance  34 . 
     In the  FIGS.  2 A  &amp; B example, the anchor  26  includes an actuator section  40 , a grip member section  42  and a contingency release section  44 . These sections  40 ,  42 ,  44  are identified herein as “sections” merely for convenience in describing the anchor  26  according to functions performed by its components. It is not necessary for the sections  40 ,  42 ,  44  to be separate and distinct divisions of the anchor  26 , and the anchor may include other or different sections in other examples. Thus, the scope of this disclosure is not limited to use of any particular number, configuration, arrangement or combination of sections in the anchor  26 . 
     An outer housing  46  is connected between upper and lower connectors  48 ,  50 . The upper connector  48  connects the anchor  26  to the conveyance  34 . The lower connector  50  connects the anchor  26  to the well tool  24 . 
     A central flow passage  52  extends longitudinally through the conveyance  34 , the anchor  26  and the well tool  24  in the  FIGS.  2 A  &amp; B example. A generally tubular inner mandrel  54  encloses the flow passage  52  in the anchor  26  between the upper and lower connectors  48 ,  50 . 
     A central axis  56  extends longitudinally through the anchor  26 . Note that it is not necessary for the central axis  56  to be positioned at precisely a geometric center of the anchor  26 . In some examples, the central axis  56  could be offset laterally relative to the geometric center of the anchor  26 . 
     The actuator section  40  is used to extend the grip members  30  (see  FIG.  1   ) of the grip member section  42  outwardly in a preliminary step of setting the anchor  26 . When the fluid  38  is flowed through the flow passage  52  at or above a selected flow rate, the actuator section  40  will cause the grip members  30  to extend outward. When the flow rate is subsequently decreased to below the selected flow rate, the actuator section  40  will cause the grip members  30  to retract inward. 
     The grip member section  42  houses the grip members  30  and includes mechanical linkages  58  that displace the grip members inward or outward in response to forces exerted by the actuator section  40 . When the grip members  30  are retracted, they are recessed relative to the outer housing  46 , so that they are protected during conveyance into and out of the wellbore  18 . 
     The contingency release section  44  is used to allow unsetting of the anchor  26  in the event that a “normal” unsetting procedure does not accomplish unsetting of the anchor. In this example, the normal unsetting procedure is to relieve the tensile force T applied to the anchor  26  via the conveyance  34  (e.g., by slacking off on the conveyance at the surface), and reduce the flow rate of the fluid  38  through the flow passage  52 , thereby causing the actuator section  40  to retract the grip members  30 . 
     Referring additionally now to  FIGS.  3 A-C , the respective actuator, grip member and contingency release sections  40 ,  42 ,  44  are representatively illustrated in a run-in configuration. In this configuration, the anchor  26  can be conveyed into the tubular string  12  by the conveyance  34 , with the grip members  30  retracted. The run-in configuration can also be considered as an “unset” configuration, since the anchor  26  is not secured against longitudinal displacement relative to the tubular string  12 . 
     In  FIG.  3 A , it may be seen that, in this example, the actuator section  40  includes an annular piston  60  sealingly received between the inner mandrel  54  and the outer housing  46 . The piston  60  is connected to an actuator sleeve  62  extending downwardly to the grip member section  42 . The piston  60  and actuator sleeve  62  are biased upward by a biasing device  64  (such as, a coiled compression spring, a compressed gas chamber, a resilient material, etc.). 
     An upper side of the piston  60  is exposed to fluid pressure in the flow passage  52  via ports  66  in the inner mandrel  54 . A lower side of the piston  60  is exposed to fluid pressure on an exterior of the anchor  26 , for example, via an alignment slot  68  (see  FIGS.  3 B  &amp; D) formed in the outer housing  46 . 
     Thus, when pressure in the flow passage  52  is greater than pressure on the exterior of the anchor  26 , this pressure differential is applied across the piston  60 , and the piston and actuator sleeve  62  are biased downward against an upwardly directed force exerted by the biasing device  64 . When the downward force exerted due to the pressure differential across the piston  60  exceeds the upward biasing force exerted by the biasing device  64 , the piston and actuator sleeve  62  will displace downward. If the downward force exerted due to the pressure differential across the piston  60  is subsequently reduced (for example, by reducing the pressure differential), so that it is exceeded by the upward biasing force exerted by the biasing device  64 , the piston and the actuator sleeve  62  will displace upward to the  FIG.  3 A  run-in and unset configuration. 
     Pressure in the flow passage  52  can be increased relative to pressure on the exterior of the anchor  26  by increasing a flow rate of the fluid  38  (see  FIG.  1   ) through the flow passage  52 . The fluid  38  will flow from the flow passage  52  to the exterior of the anchor  26  (such as, via the well tool  24  or other flow path). Fluid friction and/or a suitably configured orifice in the flow path between the flow passage  52  and the exterior of the anchor  26  will result in the pressure in the flow passage being greater than the pressure on the exterior of the anchor. 
     In  FIG.  3 B , it may be seen that the grip member section  42  includes the linkages  58  used to displace the grip members  30  (not visible in  FIG.  3 B , see  FIGS.  4 B &amp;  5   ) between their extended and retracted positions. The linkages  58  (specifically, the links  58   a ) are connected to the actuator sleeve  62 . A fastener  70  (see  FIG.  3 D ) or other projection attached to the actuator sleeve  62  extends outward into longitudinally sliding engagement with the alignment slot  68  formed in the outer housing  46 . In this manner, rotational alignment is maintained between the outer housing  46  and the actuator sleeve  62 , while permitting longitudinal displacement of the actuator sleeve relative to the outer housing. 
     When the actuator sleeve  62  displaces downward, the connected linkages  58  extend outward. When the actuator sleeve  62  subsequently displaces upward, the connected linkages  58  retract inward. As described more fully below, the linkages  58  are configured in a manner that provides for a relative large distance of extension and retraction of the grip members  30 . 
     Lower ends of the linkages  58  are connected to a support sleeve  72 . The support sleeve  72  supports the lower ends of the linkages  58 , with relative longitudinal displacement between the support sleeve and the outer housing  46  being prevented during the setting procedure. 
     Thus, when the actuator sleeve  62  displaces downward, the linkages  58  are longitudinally compressed between the actuator sleeve and the support sleeve  72 , thereby extending the grip members  30  outward. When the actuator sleeve  62  displaces upward, the linkages  58  are longitudinally extended between the actuator and support sleeves  62 ,  72 , thereby inwardly retracting the grip members  30 . 
     In  FIG.  3 C , it may be seen that the contingency release section  44  includes shear members  74  (such as, shear screws, shear pins, a shear ring, etc.) that releasably secure the support sleeve  72  relative to the outer housing  46 . The shear members  74  will shear and thereby permit the outer housing  46  to displace upward relative to the support sleeve  72  if a sufficient upwardly directed tensile force T is applied to the anchor  26  (such as, via the conveyance  34 ). In other examples, the shear members  74  could be replaced by other types of releasable attachments, latches, collets, snap rings, etc. 
     An alignment key  76  that displaces with the support sleeve  72  is in longitudinally sliding engagement with an alignment slot  78  in the outer housing  46 . Thus, rotational alignment between the support sleeve  72  (and the connected linkages  58 ) is maintained by the alignment key and slot  76 ,  78 , while longitudinal displacement of the outer housing  46  relative to the support sleeve  72  is permitted after the shear members  74  are sheared. 
     Note that the tensile force T sufficient to shear the shear members  74  would only be applied in this example if the anchor  26  is set in the well, and cannot subsequently be unset by the normal procedure of reducing the flow rate through the passage  52  and relieving the tensile force T previously applied to set the anchor. In such situations, the tensile force T can be increased to a sufficient level to shear the shear members  74  and unset the anchor  26  in a contingency release operation, described more fully below. 
     Referring additionally now to  FIGS.  4 A-C , the anchor  26  sections  40 ,  42 ,  44  are representatively illustrated in a set configuration, in which the grip members  30  are engaged with the tubular string  12 , so that relative longitudinal displacement of the anchor relative to the tubular string is prevented. If the anchor  26  is used in systems and methods other than the  FIG.  1    system  10  and method, the grip members  30  may engage another tubular string (such as, a casing, pipe, conduit, tubing, liner, etc.), another type of tubular, or an interior surface of an earth formation penetrated by a wellbore. Thus, the scope of this disclosure is not limited to engagement between the grip members  30  and any particular structure in a well. 
     In  FIG.  4 A , it may be seen that, as the flow rate of the fluid  38  through the flow passage  52  increases, the pressure differential across the piston  60  increases, and the piston and actuator sleeve  62  are increasingly biased downward. When a predetermined flow rate is achieved, the piston  60  and actuator sleeve  62  are displaced downward, and the biasing device  64  is compressed. This downward displacement of the actuator sleeve  62  causes the linkages  58  to outwardly extend the grip members  30 . 
     In  FIG.  4 B , it may be seen that, with the actuator sleeve  62  downwardly displaced as described above, the linkages  58  are longitudinally compressed between the actuator and support sleeves  62 ,  72 . This longitudinal compression of the linkages  58  displaces the grip members  30  outward into contact with the interior surface  32  of the tubular string  12 . 
     With the grip members  30  contacting the interior surface  32  of the tubular string  12 , the upwardly directed tensile force T applied to the anchor  26  will cause the linkages  58  to increasingly bias the grip members  30  against the interior surface. In this manner, the grip members  30  will “bite into” or otherwise increasingly grip the interior surface  32 . 
     In other examples, the grip members  30  may not bite into the interior surface  32  in response to application of the tensile force T. In some examples, the grip members  30  could engage a suitable profile in the tubular string  12  or otherwise contact the tubular string in a manner that secures the anchor  26  against longitudinal displacement relative to the tubular string. 
     In  FIG.  4 C , it may be seen that the contingency release section  44  remains in the same configuration as depicted in  FIG.  3 C . Thus, the support sleeve  72  continues to support the lower ends of the linkages  58  while the anchor  26  is set in the tubular string  12 . 
     Referring additionally now to  FIG.  5   , a portion of the grip member section  42  is representatively illustrated in the set configuration. The outer housing  46  is not shown in  FIG.  5    for clarity, but in the set configuration the linkages  58  and grip members  30  extend outwardly through windows or openings  80  formed in the outer housing  46  (see  FIGS.  4 B &amp;  6   ). 
     In the  FIG.  5    example, the grip member section  42  includes three sets of linkages  58  and grip members  30  evenly spaced circumferentially about the grip member section. Other numbers and configurations of the linkages  58  and grip members  30  may be used in other examples. 
     Each of the linkages  58  includes multiple arms or links  58   a,b  pivotably connected to each other and to the actuator and support sleeves  62 ,  72 . More specifically, an upper link  58   a  of each linkage  58  is pivotably connected to the actuator sleeve  62  at a pivot  82  having a pivot axis  82   a , a lower link  58   b  of each linkage is pivotably connected to the support sleeve  72  at a pivot  84  having a pivot axis  84   a , and the links  58   a,b  are pivotably connected to each other at a pivot  86  having a pivot axis  86   a . The pivot axes  82   a ,  84   a ,  86   a  are parallel to each other. 
     Thus, the links  58   a,b  of each linkage  58  form a type of “scissors” arrangement, in which longitudinal compression of the linkage results in the pivot  86  being displaced outward, and in which longitudinal extension of the linkage results in the pivot  86  being displaced inward. In the  FIG.  5    example, the grip member  30  is integrally formed on the upper linkage link  58   a  near the pivot  86 , so that the grip member displaces inward and outward with the pivot  86 . 
     However, in other examples, the grip member  30  may be separately formed from the linkage links  58   a,b  and/or may be otherwise positioned relative to the links. The linkage  58  may include different numbers, combinations or configurations of links, and may not be in a scissors arrangement. Thus, the scope of this disclosure is not limited to the details of the linkages  58  as described herein or depicted in the drawings. 
     Referring additionally now to  FIG.  6   , a cross-sectional view of the grip member section  42  is representatively illustrated, taken along line  6 - 6  of  FIG.  5   . In this view, it may be seen that the linkages  58  are distributed circumferentially about, but are laterally offset relative to, the central axis  56 . This feature enables the linkages  58  to extend farther outward in response to longitudinal compression than if the linkages were aligned with the central axis  56 . 
     In the  FIG.  6    example, the linkages  58  do not lie in planes that intersect the central axis  56 . Instead, each set of the links  58   a,b  pivot in a plane  88  that is laterally offset relative to the central axis  56 . 
     In the set configuration depicted in  FIG.  6   , the central axis  56  is positioned between each set of the pivots  84   a ,  86   a . The central axis  56  can also be positioned between each set of the pivots  82   a ,  86   a  (for example, if the pivots  82   a  are similarly positioned relative to the pivots  86   a  as the pivots  84   a , as depicted in  FIG.  5   ). 
     Referring additionally now to  FIG.  7   , the grip member and contingency release sections  42 ,  44  are representatively illustrated after the contingency release operation has been performed to unset the anchor  26 . In this configuration, the tensile force T applied to the anchor  26  has been increased to a level sufficient to shear the shear members  74 . 
     The outer housing  46  has displaced upward relative to the support sleeve  72  (the support sleeve can also displace downward relative to the outer housing  46 ), so that the linkages  58  are longitudinally extended. This longitudinal extension of the linkages  58  causes the grip members  30  to be retracted inward and out of engagement with the tubular string  12 . The BHA  22  and conveyance  34  (see  FIG.  1   ) can now be retrieved from the well to the surface. 
     It may now be fully appreciated that the above disclosure provides significant advancements to the art of constructing and utilizing anchors for securing well tools in wells. In examples described above, the anchor  26  is provided with grip members  30  that can be extended a relatively large distance outward into engagement with the interior surface  32  of the tubular string  12 , the anchor is set with a pressure differential and a tensile force T applied to the anchor, and the anchor can be unset with a contingency release procedure. 
     The above disclosure provides to the art an anchor  26  for securing a well tool  24  in a subterranean well. In one example, the anchor  26  can comprise a longitudinally extending central axis  56 , at least one outwardly extendable grip member  30 , and at least one mechanical linkage  58  including multiple pivotably connected links  58   a,b  for displacing the grip member  30 . The links  58   a,b  pivot relative to each other in a plane  88  laterally offset from the central axis  56 . 
     The links  58   a,b  may be pivotably connected at multiple pivot axes  82   a ,  84   a ,  86   a , with the central axis  56  positioned between the pivot axes  82   a ,  84   a ,  86   a . The links  58   a,b  may be laterally offset from the central axis  56 . 
     The “at least one” grip member  30  may comprise multiple grip members  30 . The multiple grip members  30  may be positioned at a same longitudinal position along the central axis  56 . 
     A flow passage  52  may extend longitudinally through the anchor  26 . The central axis  56  may be positioned in the flow passage  52 . 
     The grip member  30  may extend outward in response to a fluid flow rate increase through a longitudinal flow passage  52  of the anchor  26 . The grip member  30  may retract inward in response to a decrease in the fluid flow rate through the longitudinal flow passage  52 . 
     One of the links  58   b  may be supported by a support structure (such as support sleeve  72 ). The support structure  72  may be releasably secured relative to a housing  46 . Relative longitudinal displacement between the support structure  72  and the housing  46  may be permitted in response to a predetermined force T applied to the housing  46 . 
     A method of anchoring a well tool  24  in a subterranean well is also provided to the art by the above disclosure. In one example, the method can comprise: flowing a fluid  38  through an anchor  26  connected to the well tool  24 , thereby outwardly extending at least one grip member  30  of the anchor  26  into contact with a well surface  32 ; and applying a tensile force T to the anchor  26 , thereby increasingly biasing the grip member  30  against the well surface  32  and securing the well tool  24  relative to the well surface  32 . 
     The tensile force T applying step may include applying the tensile force T from the anchor  26  to a tubular string  12  surrounding the anchor  26 . 
     The method may include cutting the tubular string  12  while the tensile force T is applied from the anchor  26  to the tubular string  12 . 
     The fluid  38  flowing step may include creating a pressure differential across a piston  60  of the anchor  26 . The piston  60  may be connected to at least one mechanical linkage  58 . The grip member  30  outwardly extending step may include the mechanical linkage  58  outwardly extending the grip member  30  in response to the pressure differential creating step. 
     Links  58   a,b  of the mechanical linkage  58  may pivot in a plane  88  that is laterally offset relative to a central longitudinal axis  56  of the anchor  26 . 
     The method may include decreasing flow of the fluid  38  through the anchor  26 , thereby inwardly retracting the grip member  30 . 
     The method may include inwardly retracting the grip member  30  in response to increasing the tensile force T to a predetermined level. 
     The “at least one” grip member  30  may comprise multiple grip members  30 , and the outwardly extending step may include the multiple grip members  30  contacting the well surface  32  at a same longitudinal location along the well surface  32 . 
     A method of anchoring a tubing cutter  24  in a tubular string  12  in a subterranean well is also described above. In one example, the method can comprise: connecting an anchor  26  to the tubing cutter  24 ; deploying the anchor  26  and the tubing cutter  24  into the tubular string  12 ; applying a tensile force T from the anchor  26  to the tubular string  12 ; and cutting the tubular string  12  while the tensile force T is applied from the anchor  26  to the tubular string  12 . 
     The tensile force T applying step may include increasingly biasing at least one grip member  30  of the anchor  26  against an interior surface  32  of the tubular string  12 . 
     The method may include flowing a fluid  38  through the anchor  26 , thereby outwardly extending at least one grip member  30  from the anchor  26  into contact with the tubular string  12 . 
     The method may include inwardly retracting the grip member  30  in response to a decrease in flow of the fluid  38  through the anchor  26 . 
     The fluid flowing step may include creating a pressure differential across a piston  60  of the anchor  26 . The piston  60  may be connected to at least one mechanical linkage  58 , and the grip member  30  outwardly extending step may include the mechanical linkage  58  outwardly extending the grip member  30  in response to the pressure differential creating step. 
     Links of the mechanical linkage  58  may pivot in a plane  88  that is laterally offset relative to a central longitudinal axis  56  of the anchor  26 . 
     The method may include inwardly retracting the grip member  30  in response to increasing the tensile force T to a predetermined level. 
     The “at least one” grip member  30  may comprise multiple grip members  30 . The outwardly extending step may include the multiple grip members  30  contacting the tubular string  12  at a same longitudinal location along the tubular string  12 . 
     Although various examples have been described above, with each example having certain features, it should be understood that it is not necessary for a particular feature of one example to be used exclusively with that example. Instead, any of the features described above and/or depicted in the drawings can be combined with any of the examples, in addition to or in substitution for any of the other features of those examples. One example&#39;s features are not mutually exclusive to another example&#39;s features. Instead, the scope of this disclosure encompasses any combination of any of the features. 
     Although each example described above includes a certain combination of features, it should be understood that it is not necessary for all features of an example to be used. Instead, any of the features described above can be used, without any other particular feature or features also being used. 
     It should be understood that the various embodiments 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 this disclosure. The embodiments are described merely as examples of useful applications of the principles of the disclosure, which is not limited to any specific details of these embodiments. 
     In the above description of the representative examples, directional terms (such as “above,” “below,” “upper,” “lower,” etc.) are used for convenience in referring to the accompanying drawings. However, it should be clearly understood that the scope of this disclosure is not limited to any particular directions described herein. 
     The terms “including,” “includes,” “comprising,” “comprises,” and similar terms are used in a non-limiting sense in this specification. For example, if a system, method, apparatus, device, etc., is described as “including” a certain feature or element, the system, method, apparatus, device, etc., can include that feature or element, and can also include other features or elements. Similarly, the term “comprises” is considered to mean “comprises, but is not limited to.” 
     Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the disclosure, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of this disclosure. For example, structures disclosed as being separately formed can, in other examples, be integrally formed and vice versa. 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 invention being limited solely by the appended claims and their equivalents.