Patent Publication Number: US-11047192-B2

Title: Downhole positioning and anchoring device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application that claims priority to, and the benefit of, U.S. patent application Ser. No. 15/147,755, entitled “Downhole Positioning And Anchoring Device”, filed May 5, 2016, which claims priority to Provisional Application No. 62/157,292, entitled “Downhole Positioning And Anchoring Device”, filed May 5, 2015, and is a continuation-in-part of U.S. Pat. No. 9,416,609, entitled “Tool Positioning And Latching System, issued on Aug. 16, 2016, and U.S. Pat. No. 9,863,235, entitled “Permanent Or Removable Positioning Apparatus And Method For Downhole Tool Operations”, issued on Jan. 1, 2018, all of which are incorporated herein in their entireties by reference. 
    
    
     FIELD OF THE INVENTION 
     This application relates, generally, to downhole tools and methods of positioning such downhole tools within a wellbore. More particularly, the application relates to apparatus and methods to selectively position and maintain a downhole tool at a location relative to a known downhole reference location. 
     BACKGROUND 
     Many wellbore operations require cutting of metallic objects, such as tubing, casing, drill pipe or coiled tubing, in order to release the objects and any associated tools for removal from the wellbore. For example, when conducting drilling operations, it is not uncommon for a drill bit to become stuck. In such a situation, it may be desirable to cut the drill pipe at a location above the drill bit, such that the drill pipe can be retrieved, the drill bit fixed, and drilling operations can be resumed. Cutting efficiency and the necessity of salvaging equipment in close proximity to the drill bit (such as steering equipment, logging equipment, sensors, and other tools) may result in a desire to make the cut at a precise location along the drill string, such as at a joint between two sections of pipe in the drill string or even at a particular thread location in such a joint. 
     This type of precision may also be necessary for other downhole cutting activities. For example, a cut-to-release packer may provide a window of only a few inches within which a circumferential cut must be made in order to retract the packer&#39;s slips and retrieve the packer from the wellbore. Similarly, certain operations may require multiple cuts that must be made at the same location on different trips. Other downhole cutting and non-cutting operations require similar precision in tool placement. 
     In addition, even when a downhole tool can be placed at a desired location, it is often difficult to maintain the position for the duration of the operation. For example, cutting torches that produce a high pressure jet of gases during operation often create a fluid imbalance that results in the axial movement of the tool and an undesirable cut. To overcome these challenges, it is often necessary to perform a pre-cut operation to allow for fluid balancing between the drill string and the annulus. This requires a separate trip into the wellbore for the pre-cut operation prior to the necessary cutting operation. 
     While the tools required for these operations can be lowered into the wellbore from the surface using a measurable length of slickline, wireline, coiled tubing, or pipe, there are often difficulties in determining the precise location of the tool due to the elasticity of the lowering material. A small degree of elasticity (which is often an unknown parameter) may result in an unacceptably large error in calculated depth at the depths at which many of these operations take place. Such errors are exacerbated in deviated wells. Accordingly, it is difficult to know the location of a downhole tool with the precision that is required. Existing solutions, such as no-go shoulders, function by intentionally creating an undesirable restriction in the downhole conduit. Moreover, existing solutions do not address the problem of maintaining a downhole tool in the desired location throughout the duration of the operation. 
     There is therefore a need for methods and apparatus to position a downhole tool with a high degree of precision and to maintain the location of the tool throughout a downhole operation. 
     SUMMARY 
     The present invention relates, generally, to apparatus and methods usable for selectively positioning downhole tools within a wellbore and maintaining the downhole tools at a location relative to a known downhole reference location. 
     Embodiments of the present invention can include a downhole tool, such as an anchor tool, that can be positioned downhole and within a wellbore. The anchor tool can comprise a body, which can be configured to be disposed within a conduit in the wellbore, and one or more blades, which can be configured to move radially relative to the body. In an embodiment, at least one of the one or more blades can comprise a key, which can include a fixed protrusion that can be configured to match a corresponding groove of an anchor sub receptacle positioned within the conduit. The anchor tool can further include a locking mechanism that can comprise a first state and a second state, wherein the first state can permit radial movement of the one or more blades relative to the body of the anchor tool, and the second state can inhibit radial movement of the one or more blades relative to the body of the anchor tool. In an embodiment, the locking mechanism can be configured to switch to the second state from the first state as soon as the fixed protrusion extends into the corresponding groove of the anchor sub receptacle. 
     In an embodiment, the anchor tool can comprise a first end that can be configured to connect a job-specific tool to the body of the downhole anchor tool. The body of the anchor tool can further include two half cylindrical portions that can be configured to disassemble for replacement of the one or more blades, replacement of a shear pin, or combinations thereof. 
     In an embodiment of the present invention, the anchor tool can include a spring that can be configured to bias the one or more blades toward an extended radial position relative to the body. 
     In an embodiment of the anchor tool, the one or more blades can comprise a pivoting protrusion that can be configured to rotate about a connection to each of the one or more blades. The rotation of the pivoting protrusion to a fully retracted position can transition the locking mechanism to the second state. 
     In an embodiment of the anchor tool, one or more of the paired blades can be positioned opposite each of the one or more blades and can be configured to match with, and lock into, a corresponding paired anchor sub receptacle when the locking mechanism transitions to the second state. The blade can comprise a shear pin receptacle and the locking mechanism can comprise a shear pin that can be configured to align with and extend into the shear pin receptacle, when the locking mechanism is in the second state. 
     In an embodiment of the anchor tool, the locking mechanism can comprise one or more shear pin housings, and each of the one or more shear pin housings can be configured to contain additional shear pins. In an embodiment, the locking mechanism can be configured to activate only when the anchor tool is traveling in an uphole direction within the conduit. 
     In an embodiment of the anchor tool, an alignment of the one or more shear pins and the one or more shear pin receptacles can require a correct radial positioning of the one or more blades relative to the body of the anchor tool, and a correct axial positioning of the one or more shear pin housings relative to the one or more blades. An axial positioning of the one or more shear pin housings can be accomplished via a rotation of one or more pivoting members attached to the one or more blades. 
     The embodiments of the present invention can include methods for selectively positioning a downhole tool. The steps of the method can include: positioning an anchor sub along a conduit in a wellbore, wherein the anchor sub can comprise one or more grooves that define an anchor sub receptacle, and connecting the downhole tool to an anchor tool for selectively positioning the downhole tool in the wellbore. The anchor tool can comprise: a body that can be configured to be disposed within the conduit, and one or more blades that can be configured to move radially relative to the body, wherein at least one of the one or more blades can comprise a key, which can include a fixed protrusion that can be configured to match the one or more grooves of the anchor sub receptacle. The anchor tool can include a locking mechanism that can comprise a first state and a second state, wherein the first state can permit radial movement of the blade relative to the body and the second state can inhibit radial movement of the one or more blades relative to the body. The steps of the method can further include lowering the downhole tool into the tubular string until the anchor tool and the anchor sub receptacle are aligned, and locking the locking mechanism into the second state as soon as the fixed protrusion extends into the one or more grooves of the anchor sub receptacle. 
     In an embodiment, the method for selectively positioning a downhole tool can include connecting the downhole tool to the anchor tool by connecting a rigid connecting device between the downhole tool and the anchor tool. The length of the rigid connecting device can correspond to a known distance between a location of the anchor sub receptacle and a location of an intended downhole operation using the downhole tool. 
     In an embodiment of the method for selectively positioning a downhole tool, the downhole tool can be positioned above the anchor tool when the downhole tool is lowered into the tubular string. In an embodiment, the downhole tool can be lowered passed a non-matching anchor sub receptacle before the anchor tool and the anchor sub receptacle are aligned. 
     In an embodiment, the anchor tool can comprise: a cylindrical body configured to be positioned in a wellbore conduit, a first blade that can extend through a first slot on the body and can include one or more fixed protrusions and a pivoting protrusion, and a second blade that can extend through a second slot on the body and can include one or more fixed protrusions and a pivoting protrusion. The first blade and the second blade can be configured to move radially relative to the body of the anchor tool. The anchor tool can further include a locking mechanism that can be configured to inhibit radial movement of the first blade, the second blade, or combinations thereof, when the one or more fixed protrusions of the first blade and the one or more fixed protrusions of the second blade are engaged in corresponding grooves in the wellbore conduit, and when the pivoting protrusion of the first blade and the pivoting protrusion of the second blade are retracted. 
     In an embodiment of the anchor tool, the locking mechanism can comprise a shear pin housing that can be configured to move axially with respect to the first blade or the second blade when the pivoting protrusion of the first blade or the pivoting protrusion of the second blade is retracted. In an embodiment, axially moving the shear pin housing with respect to the first blade or the second blade by the pivoting protrusion of the first blade or the pivoting protrusion of the second blade can cause an alignment of the shear pin housing with a corresponding shear pin receptacle disposed in the first blade or the second blade. The locking mechanism can comprise two shear pins, and each shear pin can be disposed in a shear pin housing. 
     An embodiment of the present invention can include an anchor tool, which can comprise a body configured to be disposed within a conduit in a wellbore, and a blade that can be configured to move radially relative to the body of the anchor tool. The blade can comprise a key, which can have a fixed protrusion that can be configured to match a corresponding groove of an anchor sub receptacle within the conduit in the wellbore. A sliding protrusion can be configured to move radially and axially relative to the body of the anchor tool, and the anchor tool can further include a locking mechanism. The locking mechanism can comprise a first state and a second state, wherein the first state can permit radial movement of the blade relative to the body, and the second state can inhibit radial movement of the blade relative to the body. In an embodiment, the locking mechanism can be configured to switch to the second state from the first state when the fixed protrusion is extended into the corresponding groove and the sliding protrusion are positioned in a first axial position relative to the body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of anchor subs disposed within a conduit in accordance with an embodiment of the disclosure. 
         FIG. 2A   2 B are cutaway views of anchor subs in accordance with embodiments of the disclosure. 
         FIGS. 3A and 3B  are an isometric view and a side view, respectively, of an anchor tool in a fully extended position in accordance with an embodiment of the disclosure. 
         FIGS. 4A and 4B  are an isometric view and a side view, respectively, of an anchor tool in a fully retracted position in accordance with an embodiment of the disclosure. 
         FIGS. 5A and 5B  are an isometric view and a side view, respectively, of an anchor tool in a locked position in accordance with an embodiment of the disclosure. 
         FIG. 6  is a cutaway isometric view showing the internals of an anchor tool in accordance with an embodiment of the disclosure. 
         FIGS. 7A and 7B  are side views showing the locking mechanisms of an anchor tool in the fully extended and locked positions, respectively, in accordance with an embodiment of the disclosure. 
         FIG. 8A  is an isometric view of a shear pin housing of an anchor tool in accordance with an embodiment of the disclosure. 
         FIG. 8B  is an exploded view of the shear pin housing of the embodiment of the anchor tool shown in  FIG. 8A . 
         FIGS. 9A and 9B  are an isometric view and a side view, respectively, of an anchor tool in a fully extended position in accordance with an embodiment of the disclosure. 
         FIGS. 10A and 10B  are an isometric view and a side view, respectively, of an anchor tool in a fully retracted position in accordance with an embodiment of the disclosure. 
         FIG. 11  is a side view of an anchor tool in an unarmed position in accordance with an embodiment of the disclosure. 
         FIG. 12  is a side view of an anchor tool in an armed position in accordance with an embodiment of the disclosure. 
         FIGS. 13A and 13B  are an isometric view and a side view, respectively, of an anchor tool in a locked position in accordance with an embodiment of the disclosure. 
         FIG. 14  is a cutaway isometric view showing the internals of an anchor tool in accordance with an embodiment of the disclosure. 
         FIGS. 15A through 15D  are schematic diagrams of the internals of an anchor tool in various states of operation in accordance with an embodiment of the disclosure. 
     
    
    
     DESCRIPTION 
     Before explaining selected embodiments of the present invention in detail, it is to be understood that the present invention is not limited to the particular embodiments described herein, and that the present invention can be practiced or carried out in various ways. The disclosure and description herein is illustrative and explanatory of one or more presently preferred embodiments and variations thereof, and it will be appreciated by those skilled in the art that various changes in the design, organization, order of operation, means of operation, equipment structures and location, methodology, and use of mechanical equivalents may be made without departing from the spirit and scope of the invention. 
     As well, it should be understood that the drawings are intended to illustrate and plainly disclose presently preferred embodiments to one of skill in the art, but are not intended to be manufacturing level drawings or renditions of final products and may include simplified conceptual views as desired for easier and quicker understanding or explanation. As well, the relative size and arrangement of the components may differ from that shown and still operate within the spirit of the invention. 
     Moreover, it will be understood that various directions such as “upper,” “lower,” “bottom,” “top,” “left,” “right,” and so forth are made only with respect to explanation in conjunction with the drawings, and that the components may be oriented differently, for instance, during transportation and manufacturing as well as operation. Because many varying and different embodiments may be made within the scope of the concepts herein taught, and because many modifications may be made in the embodiments described herein, it is to be understood that the details herein are to be interpreted as illustrative and non-limiting. 
       FIG. 1  illustrates a conduit  110  in a potential wellbore operation. The conduit  110  may be a drill string, tubing string, well casing, or other pipe/tube that is lowered or secured within a wellbore. The conduit  110  includes anchor subs  102  that are positioned at various depths within the conduit  110  for anchoring tool operations. As will be illustrated below, anchor subs  102 A have different properties from anchor subs  102 B which enable them to accept and latch different anchor tools that are lowered into the conduit  110 . Likewise, anchor subs  102 C have different properties from anchor subs  102 A and  102 B that enable them to accept and latch further different anchor tools that are lowered into the conduit  110 . 
       FIGS. 2A and 2B  illustrate two example anchor subs  102 A and  102 B that are may be positioned in one or more known locations along the conduit  110 . In certain embodiments, the anchor subs  102 A,  102 B can include an inner wall (i.e., internal diameter)  108 A,  108 B, respectively, that matches the internal diameter of the conduit  110  such that the anchor sub  102  does not create a restriction in the conduit. The anchor subs  102 A,  102 B may include connecting mechanisms (e.g., internal and/or external threads, etc.) for connecting the anchor subs  102 A,  102 B to neighboring segments in the conduit  110 , such that anchor subs  102 A,  102 B become part of the conduit  110 . In practice, anchor subs  102 A,  1028  can be disposed along the conduit  110  at locations proximate to likely future location-critical operations as the conduit  110  is inserted into the wellbore. For example, anchor subs  102 A,  102 B can be positioned proximate to a drill bit in a drilling operation or proximate to a cut-to-release packer, each of which are likely locations of a future location-critical downhole operation. As will be shown below, because the distance between the anchor sub  102  and the location of the potential future location-critical downhole operation is known, a downhole tool can be positioned at the precise location for the operation using the anchor sub  102 . Each of the anchor subs  102 A,  102 B may include one or more circumferential grooves  106  (shown in  FIG. 2A  as  106 AA,  106 AB,  106 AC and  FIG. 28  as  106 BA,  106 BB,  106 BC). The shape and spacing of the grooves  106  along the anchor sub  102  creates an anchor sub receptacle  104  (i.e., anchor sub receptacle  104 A for anchor sub  102 A; anchor sub receptacle  104 B for anchor sub  102 B). An anchor tool that is lowered into the conduit  110 , having a key that matches an anchor sub receptacle  104 , can be held in position in the anchor sub  102 . For example, the anchor sub  102 A shows three grooves  106 AA,  106 AB, and  106 AC located at three positions, respectively. A corresponding key would have features that match to these three positions. The anchor sub  102 B of  FIG. 2B  shows three grooves  106 BA,  106 BB, and  106 BC that are located at three different positions, respectively, to match a key that is different from the key matching anchor sub  102 A. 
       FIGS. 3A and 3B  illustrate an isometric view and a side view, respectively, of an anchor tool  302  in a fully extended position. As shown, the anchor tool  302  comprises a main cylindrical portion (i.e., body)  304  that is composed of two half cylindrical portions  306 A,  306 B joined together by fastening mechanisms  307  (e.g., bolts, screw, pins, etc.), which are situated in internal connection cavities  308 . In an embodiment, the anchor tool  302  can be connected to a lowering device (e.g., wireline, slickline, coiled tubing, etc.) at a first end  303  of the cylindrical body and to the job-specific tool (e.g., a cutting torch) at a second end  305  of the cylindrical body by fastening mechanisms  307  that are situated in external connection cavities  310 . In another embodiment, the job-specific tool may not be directly coupled to the anchor tool  302 . For example, it may be desirable to connect the job-specific tool to the anchor tool  302  by means of a rigid connecting device to provide an offset between the anchor tool  302  and the job-specific tool. In such an instance, the connecting device may be disposed between the job-specific tool and the anchor tool  302  with the connecting device positioned either uphole  200  or downhole  202  of the anchor tool  302 . 
     As shown, a pair of blades  312 A,  312 B can extend radially outward  204  from the anchor tool through a slot in the cylindrical body. Throughout this specification, the term “radial”  204  is used to describe motion towards and away from the axial centerline of the cylindrical body of the anchor tool. While the described embodiments of the anchor tool include a cylindrical body, other embodiments may employ non-cylindrical bodies. Regardless of the shape of the body, the term radial  204  is used to refer to motion towards and away from the centerline along the length of the body. Similarly, the term “axial” is used to describe motion in a direction along the length of the tool body, regardless of shape. 
     In the position illustrated in  FIGS. 3A and 3B , the blades  312 A,  3128  are fully extended (i.e., protruding radially outward  204  from the body of the anchor tool to the maximum extent). As will be described in greater detail below, one or more biasing devices (e.g., springs) can force the blades  312 A,  312 B toward this extended position. When the anchor tool is inserted into the conduit  110 , however, the biasing devices are contracted because the blades track the inner wall of the conduit  110 . As such, the position illustrated in  FIGS. 3A and 3B  represents a shelf state position that is not realized while the anchor tool  302  is traversing through the conduit  110 . 
     The blades  312 A,  312 B can have one or more fixed protrusions  314  that form an anchor tool key  320 . In addition, pivoting protrusions  316 A,  316 B are affixed to the blades  312 A,  312 B, respectively, and extend outward from the body of the anchor tool  302  with the blades  312 A,  312 B. The pivoting protrusions  316 A,  316 B can additionally pivot in a plane parallel to the plane of the blades  312 A,  312 B and about a connection point between the pivoting protrusions and the blades  312 A,  312 B. As will be described in greater detail below, the pivoting protrusions  316 A,  316 B do not contribute to the profile of the anchor tool key  320  formed by the fixed protrusions  314  (See fixed protrusions  314 AA,  314 AB,  314 AC and  314 BA,  314 BB,  314 BC shown in  FIGS. 3A and 3B ), but instead serve to lock the blades  312 A,  312 B into a fixed position relative to the body  304  of the anchor tool  302  when the blades  312 A,  312 B are aligned with an anchor sub  102 A,  102 B having an anchor sub receptacle  104 A,  104 B, respectively, that matches the blades&#39; key  320 . For example, because the fixed protrusions  314 AA,  314 AB,  314 AC of the key  320  match the grooves  106 AA,  106 AB, and  106 AC of the anchor sub receptacle  104 A of anchor sub  102 A, the anchor tool  302  would be locked into place when aligned with anchor sub  102 A. Conversely, because the key  320  does not match the anchor sub receptacle  104 B, the anchor tool  302  would pass through anchor sub  102 B without being latched into place. 
     Referring to  FIGS. 4A and 4B , the anchor tool  302  is illustrated with blades  312 A,  312 B in a retracted position. In the retracted position, the anchor tool  302  is arranged and ready to traverse the conduit  110  from the top of the wellbore. During traversal, the outside edges of protrusions  314 AA,  314 AB,  314 AC,  314 BA,  314 BB,  314 BC and  316 A,  316 B are in contact with the inner wall  108  (Shown in  FIG. 4B ) of the conduit  110 . In this position, the blades  312 A,  312 B are not fixed relative to the anchor tool body. Rather, the biasing device is actively forcing the blades  312 A,  312 B outward  204  from the anchor tool body, such that the blades might extend into the grooves  106  of an anchor sub  102 A,  102 B having an anchor sub receptacle  104 A,  104 B, respectively, that matches the profile  320  formed by the protrusions  314 AA,  314 AB,  314 AC,  314 BA,  314 BB,  314 BC when the anchor tool  302  and the anchor sub  102 A,  102 B are properly aligned. 
     Referring to  FIGS. 5A and 5B , the anchor tool  302  is illustrated with blades  312 A,  312 B locked in a fixed radial position relative to the body of anchor tool  302  (e.g., between the extended and retracted positions illustrated in  FIG. 3  and  FIG. 4 , respectively). When the protrusions  314  are aligned with corresponding grooves  106  of a compatible anchor sub  102  (i.e., an anchor sub having a receptacle  104 A that matches the key  320 , such as in the case of the illustrated anchor sub  102 A) the blades  312  will extend outward. The receptacle  104 , however, does not have a groove  106  for the pivoting protrusion  316 . Instead of fitting into a groove  106 A,  106 B, the pivoting protrusions  316 A,  316 B pivot towards the body of the anchor tool  302 , such that a flat portion of the pivoting protrusions  316 A,  316 B rests against the inner wall of the conduit  110 . As will be described in greater detail below, this pivoting action results in the blades  312 A,  312 B being locked in a fixed radial position relative to the body of the anchor tool  302 . Because the blades  312 A,  312 B are locked with the fixed protrusions  314  engaged in the grooves  106  of the anchor sub  102 , the anchor tool  302  is fixed at a known location (i.e., the known location of the anchor sub). This enables a downhole operation to be performed at a precise location within the conduit  110 . That is, because an anchor sub  102 , having a known receptacle  104 , is located in a conduit at a location that is a known distance from a likely operation point (e.g., a likely cutting point), when the anchor tool  302 , having a key  320  that corresponds to the receptacle  104 , is lowered into the wellbore, it can be guaranteed that a job-specific tool, which is offset from the anchor tool  302  by the known distance, is at the precise desired depth. It should be noted that the described embodiment of the anchor tool  302  will be locked into place in the first anchor sub having a corresponding receptacle (i.e., the anchor sub having a corresponding receptacle that is closest to the surface). Other embodiments allow an anchor tool to pass through a corresponding anchor sub in one direction and to be locked into the corresponding anchor sub when traveling in a different direction. For example, another embodiment allows an anchor tool  302  to pass through a compatible anchor sub  102  when traveling in the downhole direction  202  and to be locked into the first compatible anchor sub  102  that it contacts when traveling in the uphole direction  200 . 
     Referring to  FIG. 6 , the half cylindrical body  306 A of the anchor tool  302  and the blade  312 B have been removed to reveal the internal components of the anchor tool  302 . It will be recognized that blade  312 B functions as a mirror image of blade  312 A. Accordingly, the description of the functionality with respect to blade  312 A applies equally to blade  312 B. The blade  312 A is biased outward  204  from the body of the anchor tool  302  by springs  322 . The axial position of the blade  312 A with respect to the anchor tool body is maintained by pins  324  that extend through grooves  326  in the blade  312 A. The engagement of the pins  324  within the grooves  326  enables the blade  312 A to move radially with respect to the body of the anchor tool  302  while inhibiting axial movement of the blade  312 A with respect to the anchor tool body. The pivoting protrusion  316 A moves radially with the blade  312 A and additionally pivots in a plane parallel to the plane of the blade  312 A about a pivot connection  330 A to the blade  312 A. A shear pin receptacle  328 A receives a shear pin when the blade  312 A is aligned with a compatible anchor sub  102 . 
       FIG. 7A  illustrates an embodiment of the internal components of the anchor tool  302  with the blade  312  illustrated as partially transparent in order to allow a view of the blade locking mechanisms. Blade  312  is illustrated in the fully extended position (i.e., position shown in  FIGS. 3A and 3B ). In this position, the shear pin receptacle  328  is misaligned with the shear pin  342  in both the radial direction  204  and the axial direction (i.e., downhole  202 ). Accordingly, the shear pin  342  must move in the radial direction  204  and the downhole axial direction  202  to line up with the shear pin receptacle  328  to lock the blade  312  into the fixed position with respect to the anchor tool  302  body  304 . As described above, the springs  322  can exert a radially  204  outward force on the blade  312 , causing radial  204  movement of the blade  312  and the shear pin receptacle  328 . In certain embodiments, when the blade  312  is fully extended, the shear pin receptacle  328  is radially  204  passed the shear pin  342 . However, when each of the blade&#39;s protrusions  314  are engaged in a corresponding groove  106  of an anchor sub  102 , the blade  312  is in a radial position between the fully extended and retracted positions, and the shear pin receptacle  328  and the shear pin  342  will be radially aligned. 
     The shear pin receptacle  328  and the shear pin  342  must be axially aligned, however, for the shear pin  342  to lock inside the shear pin receptacle  328 . This axial alignment requirement prevents an accidental locking of the blade  312  relative to the anchor tool body when the anchor tool  302  is not fully engaged in a compatible anchor sub  102 . If the shear pin  342  and shear pin receptacle  328  were perpetually aligned in the axial direction and latching relied solely upon the radial action of the blade  312 , any radial movement of the blade  312  from an irregularity in the inner wall of the conduit  110  or the extension of one or more protrusions  314  into the grooves  106  of a non-compatible anchor sub may result in an unintended locking of the blade  312 . 
     Locking the blade  312  from radial movement relative to the anchor tool body therefore requires not only that the protrusions  314  be fully extended into the grooves  106  of a compatible anchor sub  102  but also that the outer edge of the blade  312 , in a region  344  proximate to the pivoting protrusion  316  be in contact with the inner wall of the conduit  110 . When all of the fixed protrusions  314  of the blade  312  extend into grooves  106  of a compatible anchor sub  102 , and the pivoting protrusion  316  contacts the inner wall of the conduit  110 , the pivoting protrusion  316  rotates in the direction of the arrow  346  about pivot connection  330 , overcoming the force of a spring  332 , which opposes this rotation and biases the pivoting protrusion  316  towards its protruded position. As the pivoting protrusion  316  rotates about the pivot connection  330 , a pin  334 , which is coupled to the pivoting protrusion  316  and engaged in a carriage track  336  of a carriage  338 , moves both radially and axially relative to the body  304  of the anchor tool  302 . The movement of the pin  334  within the carriage track  336  of the carriage  338  results in the axial movement of the carriage  338  within the body  304  of the anchor tool  302 . The axial movement of the carriage  338  results in axial movement of the shear pin  342 , which is disposed within a shear pin housing  340 , that is coupled to, and moves axially with, the carriage  338 . 
     When the pivoting protrusion  316  is in the fully retracted position, as illustrated in  FIG. 7B , the axial position of the carriage  338  results in the axial alignment of the shear pin  342  and the shear pin receptacle  328 . As will be described below, the shear pin  342  can be disposed within a shear pin housing  340  that can contain a bias device (e.g., a spring) that exerts a force on the shear pin  342  in the direction of the blade  312 . When the shear pin  342  is aligned with the shear pin receptacle  328 , the shear pin  342  extends into the shear pin receptacle  328 . Because the shear pin  342  is fixed radially relative to the anchor tool body, the extension of the shear pin  342  into the shear pin receptacle  328  prevents the radial movement of the blade  312  relative to the anchor tool body  304 . Moreover, the engagement of the blade&#39;s protrusions  314  with the grooves  106  of the compatible anchor sub  102  prevents axial movement of the anchor tool  302  relative to the conduit  110 . Once locked into a compatible anchor sub  102 , the anchor tool  302  can only be released by applying a force that is great enough to shear the shear pin  342  in order to re-establish the radial movement of the blade  312 . Typically, this force will only be applied by exerting a relatively high amount of tension on the lowering device. Accordingly, when the anchor tool  302  is locked within the anchor sub  102 , the job-specific tool is both positioned at a precise location and maintained at that location for the duration of the job. 
       FIG. 8  illustrates an exploded view of the shear pin housing  340 . As shown, the shear pin housing  340  contains a shear pin rocker arm  356 . The shear pin  342  is attached to the shear pin rocker arm  356  by means of a rocker arm pin  354  that passes through the hole  366  in the shear pin  342  and the holes  368  in each of the rocker arm brackets  370 , such that rotation of the rocker arm  356  causes the shear pin  342  to extend through the hole  372  in the shear pin housing cover  360 . The rocker arm  356  can be maintained in its position, within the shear pin housing  340 , by screws  350  and  358 , which can be disposed in the sides of the housing  340 . The spring  352  can be positioned against the back wall of the housing  340  and can receive the post  364  of the shear pin  342 , which exerts an axial force on the shear pin  342  towards the cover  360  of the shear pin housing  340 , resulting in the rotation of the shear pin rocker arm  356  and the extension of the shear pin  342  through the hole  372  when the hole  372  is not obstructed by the blade  312 . As shown, the cover  360  is secured to the shear pin housing  340  by one or more fasteners (e.g., screws)  362 ; however, other means of securing the cover  360  to the shear pin housing  340  can be used. As described above, the extension of the shear pin  342  into the shear pin receptacle  328  of the blade  312  results in the restriction of the radial motion of the blade  312  relative to the anchor tool body  304 . 
       FIGS. 9A and 9B  illustrate a potential embodiment of a direction-specific anchor tool  902 . A direction-specific tool may only lock in place when traveling in a particular direction  206  and thus, the figures indicate the direction  206  of tool movement (See also  FIGS. 10A and 10B ) within the conduit  110 . The anchor tool  902  is similar in several respects to the anchor tool  302 . Like anchor tool  302 , the direction-specific anchor tool  902  is constructed from two half cylindrical portions  906 A,  906 B that can be joined via fasteners  907  disposed in internal connection cavities  308 . Likewise, anchor tool  902  includes external connection cavities  310  that allow the anchor tool to be connected to a lowering device and/or a job-specific tool, as described above. Blades  912 A,  912 B extend radially from opposing sides of the body of the anchor tool  902  and are biased towards the extended position. Each of the blades  912 A,  312 B includes one or more fixed protrusions  914  (Shown in  FIGS. 9A, 9B, 10A, and 10B  as  914 AA,  914 AB,  914 AC and  914 BA,  914 BB,  914 BC) that define an anchor tool key  320 . That is, in certain embodiments, the anchor tool  902  includes three protrusions  914 AA,  914 AB, and  914 AC located at three positions, respectively. The corresponding anchor sub  102 A would have features that match to these three positions. 
     Unlike the anchor tool  302 , the anchor tool  902  additionally includes radial sliding protrusions  916 A,  916 B that extend outward from the body of the anchor tool  902  and move radially independent of the radial movement of the blades  912 A,  912 B. The anchor tool  902  further includes axial sliding protrusions  918 A,  918 B that extend outward from a body  304  of the anchor tool  902  through slots  986 A,  986 B. The axial sliding protrusions  918 A,  918 B move both radially and axially relative to the body  304  of the anchor tool  902 . It should be noted that neither the radial sliding protrusions  916 A,  916 B nor the axial sliding protrusions  918 A,  918 B contribute to the profile of the key  320  formed by the fixed protrusions  914  of the blades  912 . 
     In  FIGS. 9A and 9B , the blades  912 A,  312 B and the sliding protrusions  916 A,  316 B and  918 A,  918 B are illustrated in the shelf state. In this state, the blades  912 A,  312 B, the radial sliding protrusions  916 A,  916 B, and the axial sliding protrusions  918 A,  918 B are fully extended in the radial direction  204  (i.e., protruding from the body of the anchor tool to the maximum extent). In addition, the axial sliding protrusions  918 A,  918 B are internally biased (e.g., via a spring applying a force) toward the uphole  200  position within the slots  986 A,  986 B. As described above and with respect to the anchor tool  302 , this shelf state position is only observed when the anchor tool  902  is located external to a conduit  110 . When the anchor tool  902  is lowered into a conduit  110  and is not aligned with a compatible anchor sub  102 , the outside edges of the fixed and sliding protrusions  914 ,  916 , and  918  contact the inner wall  108  of the conduit  110 , as illustrated in  FIGS. 10A and 10B . As will be described below, when the anchor tool  902  is being lowered into the conduit  110 , the axial sliding protrusions  918 A,  918 B maintain their axial position at the uphole end of the slots  986 A,  986 B, as is illustrated in  FIGS. 10A and 10B . In one embodiment, the axial position of the protrusions  918 A,  918 B is maintained through one or more springs that apply an axial force on the protrusions  918 A,  918 B in the uphole direction. In another embodiment, the axial position of the protrusions  918 A,  918 B is maintained by the friction between the outer edge of the protrusions  918 A,  918 B and the inner wall  108  of the conduit  110  as the anchor tool  902  is lowered into the conduit  110 . 
     Referring to  FIG. 11 , as the anchor tool  902  is lowered into the conduit  110 , it is aligned with a compatible anchor sub  102 . In this position, the protrusions  914  are aligned with corresponding grooves  106  (e.g.,  914 AA,  914 AB and  914 AC are aligned with corresponding grooves  106 AA,  106 AB and  106 AC, respectively, and  914 BA,  914 BB and  914 BC are aligned with corresponding grooves  106 BA,  106 BB and  106 BC, respectively), and the blades  912 A,  912 B extend outward. Likewise, the radial sliding protrusions  916 A,  916 B contact the inner wall  108  of the conduit. Although the anchor tool  902  is aligned with a compatible anchor sub  102 , the anchor tool  902  is not latched into place because the anchor tool  902  is moving in the downhole direction and the axially sliding protrusions  918 A,  918 B are situated in the uphole position within the slots  986 A,  986 B, respectively. Because the blades  912 A,  912 B move freely in the radial direction relative to the body of the anchor tool  902 , the anchor tool  902  passes through the compatible anchor sub  102  and continues moving in the downhole direction. This allows an operator to utilize multiple anchor subs that have a common receptacle  104  within a conduit  110 . For example, referring to  FIG. 111 , although an anchor tool  902  may be configured with blades  912  that make it compatible with anchor sub  102 A, the anchor tool  902  may pass through undesired uphole anchor subs  102 A and be latched within a desired downhole anchor sub  102 A when it is aligned with the anchor sub  102 A, while traveling in a traveling direction  206  that is in an uphole direction  200 . 
     When the anchor tool  902  is traveling  206  in an uphole direction  200  as indicated in  FIG. 12  and the axial sliding protrusions  918 A,  918 B contact one or more grooves  106  of an anchor sub  102 , the axial sliding protrusions  918 A,  918 B can expand into the one or more grooves  106 . The friction between the shoulders of the protrusions  918 A,  918 B and the groove(s)  106  can result in the axial movement of the protrusions  918 A,  918 B to the downhole end of the slots  986 A,  986 B. This position will be described as the “armed” position, as it results in the axial alignment of the shear pins with the blades&#39; shear pin receptacles and enables the blades to be latched when the anchor tool  902  is aligned with a compatible anchor sub  102 . After the anchor tool has transitioned to the armed position, the frictional force between the protrusions  918 A,  918 B and the inner wall  108  of the conduit  110  will maintain the armed position until the direction of the anchor tool  902  is reversed. While the described embodiment requires the engagement of the protrusions  918 A,  918 B within a groove(s)  106  to transition to the armed position, in another embodiment, the anchor tool  902  may be armed solely by the friction generated between an axial sliding protrusion  918 A,  918 B and the inner wall  108  of the conduit  110 . In such an embodiment, it may not be necessary for the axial sliding protrusion to move radially relative to the body of the anchor tool  902 . 
     Referring to  FIGS. 13A and 13B , when the tool  902  is armed and aligned with a compatible anchor sub  102  (shown in  FIG. 13B  as anchor sub  102 A), the protrusions  914  (shown in  FIGS. 13A and 13B  as  914 AA,  914 AB,  914 AC and ( 14 BA,  914 BB,  914 BC) can expand into corresponding grooves of the anchor sub  102 . Simultaneously, the radial sliding protrusions  916 A,  916 B can contact the inner wall  108  of the conduit  110  and retract relative to the blades  912 A,  912 B. As will be described below, these actions result in the blades  912 A,  912 B being fixed radially relative to the body of the anchor tool  902 . Because the protrusions  914  are situated in corresponding grooves  106  of the anchor sub  102  and because the blades  912  are fixed radially relative to the body of the anchor tool  902 , the anchor tool  902  is positioned and maintained at the precise location of the anchor sub  102 . It should be noted that the positions of the blades  912  and the radial sliding protrusions  916  are identical whether the tool  902  is traveling  206  in the downhole  202  or uphole  200  directions as illustrated in  FIGS. 11 and 13B , respectively. The position of the axial sliding protrusions  918 A,  918 B, however, prevents the anchor tool  902  from being latched into a compatible anchor sub when the traveling direction  206  is in the downhole direction  202  and enables it to be latched into a compatible anchor sub when the traveling direction  206  is in the uphole direction  200 . 
       FIG. 14  illustrates an embodiment of the tool  902  of  FIG. 9  having the half cylindrical portion  906 A and blade  912 B removed to provide a view of the internal structures. It will be understood that the removed items function in the same manner as the corresponding illustrated items. Blade  912 A is biased towards its fully extended position by springs  922 . Radial sliding protrusion  916 A may move independently from the blade  912 A and is shown biased towards its fully extended position (by a spring that is hidden in the illustration in  FIG. 14 ). Likewise, axial sliding protrusion  918 A may move independently from the blade  912 A and can be biased in the radial direction towards its fully extended position by a spring  980 , and biased in the uphole  200  (i.e., unarmed) direction within slot  986 A. The axial sliding protrusion  918 A is linked to a carriage  938 A. The axial movement of the axial sliding protrusion  918 A results in the axial movement of the carriage  938 A, which, in turn, results in the movement of the shear pin housing  940 A to align a shear pin within the housing with the shear pin receptacle  928 A. As shown, the alignment of the axial sliding protrusion  918 A is maintained by the use of guide pins  982  moving within slotted areas. 
     Like anchor tool  302 , anchor tool  902  requires both radial and axial motions to cause the alignment of a shear pin  942  (See  FIG. 15A ) with a shear pin receptacle  928 A disposed in the blade  912 . In  FIGS. 15A through 15D , a shear pin housing  940  is located behind a shear pin cover  990  that is attached to and moves with the radial sliding protrusion  916 . Both the shear pin housing  940  and the shear pin cover  990  are located behind the blade  912 . In one embodiment, the shear pin housing  940  may be constructed in a similar manner to shear pin housing  340  such that the shear pin  942  is biased towards the blade  912 . 
       FIG. 15A  illustrates an embodiment of possible relative positions of the internal components of the anchor tool  902  in the unarmed and retracted state (i.e., the state illustrated in  FIGS. 10A and 10B ). In this position, the shear pin  942  is misaligned with the shear pin receptacle  928  in both the axial and radial directions.  FIG. 15  shows the shear pin cover  990  for the shear pin  942 , and includes the blade  912  of the anchor tool  902 , with fixed protrusions  914  and radial sliding protrusions  916 .  FIG. 15B  illustrates the relative positions of the internal components when the anchor tool  902  is aligned with a compatible anchor sub and traveling  206  in the downhole direction (i.e., in the unarmed position illustrated in  FIG. 11 ). In this position, the protrusions  914  extend into the corresponding grooves  106  of the compatible anchor sub  102  and the radial sliding protrusion retracts relative to the blade  912 , which moves the shear pin cover  990  and exposes the shear pin  942 . However, because the anchor tool is in the unarmed position, the shear pin  942  and the shear pin receptacle  928  are misaligned in the axial direction and the blade  912  is not latched.  FIG. 15C  illustrates the relative positions of the internal components of the anchor tool  902  in the armed and retracted state (i.e., the state illustrated in  FIG. 12 ). In this position, the axial position of the axial sliding protrusion  918  (not shown) has armed the anchor tool  902  by moving the shear pin housing  940  such that the shear pin  942  and the shear pin receptacle  928  are in axial alignment. Because the tool is not aligned with a compatible anchor sub, however, there is no radial alignment of the shear pin  942  and shear pin receptacle  928 .  FIG. 15D  illustrates the relative positions of the internal components when the anchor tool  902  is latched in a compatible anchor sub. In this position, the anchor tool  902  is armed as it travels in the uphole direction, and the protrusions  914  are extended into corresponding grooves  106  of a compatible anchor sub  102 . In addition, the radial sliding protrusion is retracted relative to the blade  912  such that the shear pin cover  990  does not interfere with the engagement of the shear pin  942  into the shear pin receptacle  928 . Like the anchor tool  302 , the latched position is maintained until a force great enough to overcome the holding force of the shear pin  942  is applied to the anchor tool  902 . As such, the anchor tool  902  can traverse compatible anchor subs when traveling  206  in the downhole direction and be latched into compatible anchor subs when traveling  206  in the uphole direction, such that an attached job-specific tool can be located and maintained at a position relative to one of multiple compatible anchor subs in a wellbore conduit. 
     The anchor tools and anchor subs described herein can be provided in a variety of diameters to accommodate a variety of tasks. Typical anchor tool outside diameters range from about 19.05 mm (0.75 inches) to about 15.24 cm (6 inches), or greater. Moreover, while the described anchor tools include two blades positioned 180 degrees apart, other embodiments might include more or fewer blades positioned around the body of the anchor tool. The construction of the described anchor tool allows the blades to be efficiently changed onsite to correspond to a desired anchor sub. 
     While various embodiments of the present invention have been described with emphasis, it should be understood that within the scope of the appended claims, the present invention might be practiced other than as specifically described herein.