Abstract:
A whipstock anchor is hydraulically set and locked in the set position. Release occurs with a pull induced component failure that relieves hydraulic pressure that allows the slips to retract. Release can occur with a remotely actuated circuit that burns a retainer for a piston whose movement opens a vent or initiates a chemical reaction to undermine a lock ring. Movement of a single cone or opposed cones extends the slips. The cone angles being different (cone angles do not have to be different, it is preferred to have the slip angles different) adds a skew to the slips and positions the top of the whipstock against the tubular top in a horizontal run. A bottom cap is removable to convert to setting by set down weight or to attach a hydraulically operated packer below the slips. Slips can be extended with radial movement of pistons.

Description:
FIELD OF THE INVENTION 
       [0001]    The field of the invention is hydraulic anchor assemblies for whipstocks in borehole use and more particularly anchors that release in a variety of ways, or cock the whipstock or that can be modularly built to optionally add setting capability with setting down weight or be reconfigured to add a hydraulically actuated sealing functionality to the anchor. 
       BACKGROUND OF THE INVENTION 
       [0002]    Whipstocks are long tapered ramps that are secured in a tubular string to guide a mill assembly laterally to make an exit through the tubular wall for the start of a lateral bore. The taper angle is gradual, in the order of about 1-3 degrees. The ramp is typically oriented with a bottom hole assembly so that the ramp faces the direction of the desired lateral. In some instances there can be a need to have the lateral exit in a downward direction off a horizontal bore. In such cases it is advantageous to ensure that the top of the whipstock is pushed against the top of the horizontal run so that after the window in the casing has been milled a drilling assembly that will be deployed on a subsequent run will pass freely through the window in the casing without engaging the top of the whipstock. 
         [0003]    Anchors that hydraulically extend from one side of a whipstock lower end to skew the whipstock are described in U.S. Pat. No. 6,843,314. A design that uses a nonparallel slip face to the surrounding tubular for skewing the whipstock is described in U.S. Pat. No. 8,505,651. Another way a whipstock is mounted off center in a surrounding tubular is to use an eccentrically mounted sealing element that is set with set down weight after an anchor is set mechanically or hydraulically is shown in US 2015/0345241. A non-releasing anchor that sets hydraulically and has the set position locked with a body lock ring is shown in U.S. Pat. No. 5,154,231. A mechanically actuated whipstock anchor using relative movement of opposed inclined surfaces is shown in U.S. Pat. No. 6,360,821. 
         [0004]    What is needed and provided by the illustrated embodiments of the present invention is a hydraulic whipstock anchor that holds the set and can be released in a variety of ways. One way is to vent trapped hydraulic pressure that holds the slips out and one way that is done is to pull tension and fail a component that lets the hydraulic pressure relieve so that the slips can retract. Another way to slip release is to remotely close a circuit that allows electrical current to heat and break a wire to release a piston whose movement opens a vent port. Alternatively release of the piston can allow fluids to pass through a port that undermine a mechanical lock ring that holds the slips extended. The slips can be wedged out radially with axial movement of a cone or by radial piston movement with the slips on the piston ends. The anchor design can be modular so that removal of an end cap allows alternative slip setting by setting down weight or the ability to add a packer component to the housing end that is actuated hydraulically with the slips. Cocking of the whipstock top end to an upper part of a horizontal run for a downward casing exit can be accomplished with ramps sloped at different angles that induce a turning moment on the slips to rotate the whipstock body. Preferably the slips will be offset along the axis of the whipstock to further increase the turning moment to rotate the whipstock body. Alternatively, the slip assembly can be mounted on an axis that skews with respect to the whipstock body to impart a turning moment to the whipstock body for desired positioning of the top end of the whipstock. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiments and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims. 
       SUMMARY OF THE INVENTION 
       [0005]    A whipstock anchor is hydraulically set and locked in the set position. Release occurs with a pull induced component failure that relieves hydraulic pressure that allows the slips to retract. Release can occur with a remotely actuated circuit that burns a retainer for a piston whose movement opens a vent or initiates a chemical reaction to undermine a lock ring. Movement of a single cone or opposed cones extends the slips. The cone angles being different adds a skew to the slips and positions the top of the whipstock against the tubular top in a horizontal run. A bottom cap is removable to convert to setting by set down weight or to attach a hydraulically operated packer below the slips. Slips can be extended with radial movement of pistons. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a section view of a locking anchor design with a tensile release; 
           [0007]      FIG. 1 a    is the view along line  1   a - 1   a  of  FIG. 1   
           [0008]      FIG. 1 b    is an enlarged view of the slips in  FIG. 1  showing the taper angle difference; 
           [0009]      FIG. 2  is a section view of an alternative embodiment showing a skew in the anchor body with respect to the whipstock axis; 
           [0010]      FIG. 2 a    is the view along line  2   a - 2   a  of  FIG. 2   
           [0011]      FIG. 3  is a section view of an embodiment showing opposed cone movement for slip extension; 
           [0012]      FIG. 3 a    is the view along line  3   a - 3   a  of  FIG. 3 ; 
           [0013]      FIG. 3 b    is an outside view of the slip retainer of  FIG. 3 ; 
           [0014]      FIG. 3 c    is a detailed section view of the slips in  FIG. 3  showing differing opposed taper angles; 
           [0015]      FIG. 4  is a section view of an embodiment that releases with a remote signal that allows a piston to move to release hydraulic pressure; 
           [0016]      FIG. 4 a    is the view along line  4   a - 4   a  of  FIG. 4 ; 
           [0017]      FIG. 5  is a section view of an embodiment that moves a slip radially with a radially oriented piston and releases with a remote signal that vents hydraulic pressure; 
           [0018]      FIG. 5 a    is an outside view of the slips showing a retainer for the moving slips; 
           [0019]      FIG. 6  illustrates a modular hydraulically operated packer that can be mounted to the slip assembly; 
           [0020]      FIG. 7  is a section view of an anchor that is releases with a remote signal that allows a piston to move to release an agent to undermine a body lock ring for anchor release; 
           [0021]      FIG. 7 a    is a view along line  7   a - 7   a  of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]    Referring to  FIG. 1 , a whipstock  10  has a ramp  12  and an associated hydraulic line  14  that typically is run behind the ramp  12  to protect the line  14  from the advancing window mill that is not shown. A check valve  16  in line  14  allows flow one way into passage  18  to chamber  20  defined by cap  22  secured at thread  24  to housing  26 . Cone  32  is sealed with seals  28  and  30  so that built up pressure in chamber  20  moves cone  32  in the direction of arrow  34  toward the housing  26 . Two slips  36  are shown at 180 degree spacing although different spacing and number of slips is contemplated. The slips  36  have external carbide or hardened inserts  38  to dig into the surrounding tubular that is not shown to support the whipstock  10 . A biasing spring  40  pushes between a respective slip  36  and a retainer  42  that limits the outward travel of each slip  36 . A lock ring  44  is moved along ratchet profile  46  as cone  32  moves in the direction of arrow  34  to prevent reverse movement of the cone  32 . The lock ring  44  in effect maintains the set of the slips  36  against the surrounding tubular that is not shown. Preferably ramp surfaces  48 ,  50 ,  140  and  142  have the same slope. Slip surface  144  has a slightly smaller slope than ramp surfaces  48 ,  50 ,  140  and  142 , and slip surface  146  has a slightly greater slope than ramp surfaces  48 ,  50 ,  140  and  142  to put whipstock axis  152  into a cocked position with respect to horizontal axis  52  as schematically illustrates in  FIG. 1 b   . In a preferred embodiment the angle difference on opposed slip surfaces  144  and  146  is a degree but larger or even smaller differences are contemplated to skew the slip orientation in opposed directions as between slips with 180 degree spacing. The desired result is a skew is imparted to the whipstock  10  to keep its upper end (not shown) against the inside diameter (ID) of a horizontal pipe for making a downwardly oriented window exit. In essence the slips hardened inserts  38  are parallel to each other but both are skewed with the whipstock axis  152  to impart a rotational moment to whipstock  10  as indicated by arrows  54  and  56 . Preferably ramps surfaces  48  and  50  will be closer to the top of the whipstock than ramps surfaces  140  and  142  to provide a fulcrum effect to create a greater force to keep the top of the whipstock pushed tighter against the ID of the horizontal pipe. Preferably the sloping surfaces  144  and  146  on the slips  36  are parallel to their respective opposing ramp surfaces  48 ,  140 ,  50 , and  142  on cone  32  and housing  26  however, some angular difference is also contemplated as an option. Hardened inserts  38  are imbedded into slips  36  on either side of retainer  42 . Width  148  on one side of slip  36  is greater than width  150  on the other side of slip  36 . Having different widths on either side of slip  36  makes it possible to use identical slips at 180 degree spacing in housing  26  and have them installed in the proper orientation. Retainers  42  cannot be installed if slips  36  are installed in housing  26  incorrectly. Whipstock axis  152  will also be rotated if the slope of slip surfaces  144  and  146  are identical and housing ramp angle  48  is larger than ramp angle  140  and cone ramp angle  50  is smaller than ramp angle  142 . Mandrel  58  has a necked down portion  60  so that when a tensile force is exerted on the whipstock  10  with slips  36  extended to the surrounding tubular the cone  32  and lock ring  44  retain the lower end of the mandrel  58  because the slips  36  bite into the surrounding tubular. The tensile force on mandrel  58  increases until a tensile failure occurs at necked down portion  60 . As the mandrel  58  breaks at  60  the pressure in chamber  20  dissipates and the housing  26  has the ability to move up and away from the set slips  36  so they are no longer wedged against the surrounding tubular. The cone  32  is retained by cap  22  after the tensile failure at  60 . It should be noted if the hydraulic system is filled with incompressible fluid the check valve  16  can hold the pressure against the set slips  36  using cone  32 , however, the body lock ring  44  insures that the slips  36  cannot back away from the surrounding tubular after the set. 
         [0023]      FIG. 2  is somewhat different than  FIG. 1  in that a single radially moving slip  36  is used and is opposed by segment  62  with hardened or carbide inserts  64 . Cone  32  is modified to have a taper only under the single slip  36  whose extension brings the inserts  64  to the surrounding tubular wall. In this version the hardened inserts  38  in slip  36  are parallel to hardened inserts  64  in segment  62 , but are at a small angle with respect to whipstock axis  152  of the whipstock  10  such that extension of slip  36  until inserts  64  reach the surrounding tubular 180 degrees away will wind up pushing the top end of the whipstock against the surrounding pipe to keep it out of the way of the advancing window mill. Housing  26  is conically shaped below arrows  66  to provide clearance when the bottom of the whipstock  10  is rotated toward the tubing wall. The skew in  FIG. 2  can be further enhanced with the orienting of the one slip  36  akin to the manner previously described in the discussion of  FIG. 1   b.    
         [0024]      FIG. 3  is the same as  FIG. 1  with the exception that there are opposed pistons that move on opposite sides of the slips  36 . Mandrel  58  that was threaded to housing  26  in  FIG. 1  is now slidably mounted after breaking shear pin  68 . A lock ring  70  only allows mandrel  58  to move in the direction of arrow  72  with its final position locked in with lock ring  70 . As before cone  32  moves in an opposite direction toward slips  36  and its set position is locked with lock ring  44 . Pin  74  extends from housing  26  into slot  76  in mandrel  58  to prevent relative rotation between the two. As before release occurs with a tensile failure at decked down portion  60  in response to a tensile force on whipstock  10 . 
         [0025]    In  FIG. 4  the arrangement of the gripping is the same as  FIG. 2  in that there is a slip  36  located 180 degrees opposite a segment  62  with hardened or carbide inserts  64 . As before pressure in line  14  goes through check valve  16  and against piston  80  that has a peripheral seal  82 . Spring  84  pushes piston  80  away from slip  36  until the spring force is overcome with pressure in line  14 . Piston  80  has a through bore  78  blocked by plug  86  that has a seal  88 . A battery and signal receiver  90  gets a remote signal to close a circuit which then heats a wire  92  operatively connected to retainer  94  to defeat it which constitutes the trigger so that plug  86  can move and take seal  88  past vent passage  96  to relieve the pressure above piston  80  which in essence allows spring  84  to push piston  80  away from slip  36  to allow removal of the whipstock  10  without well intervention which means avoiding sticking tools in the borehole to accomplish the task. Again in this version the hardened inserts  38  in slip  36  are parallel to hardened inserts  64  in segment  62 , but are at a small angle with respect to whipstock axis  152  of the whipstock  10  such that extension of slip  36  until inserts  64  reach the surrounding tubular 180 degrees away will wind up pushing the top end of the whipstock against the surrounding pipe to keep it out of the way of the advancing window mill. Surface  98  is stationary as the slip  36  is guided at end  100  by a rail or dovetail. In this design the line  14  pressure held by check valve  16  holds the set position of the slip  36 . 
         [0026]    The signal can be sent without well intervention in a variety of known ways such as acoustic, electromagnetic, mud pulse or vibration. A fixed lug retrieval tool that engages the whipstock for whipstock retrieval could mechanically close a circuit that would initiate opening of the trigger. The fixed lug retrieval tool could include a magnet that activates a sensor in the whipstock. Using the fixed lug retrieval tool to initiate pressure release could include running a wire from the whipstock to the battery. That is, a sensor is optional in the anchor. Closing the circuit to active the pressure release could be controlled from the whipstock instead of at the anchor. 
         [0027]      FIG. 5  uses line  14  and check valve  16  to feed pressure to radially extend pistons  110  that each have hardened or carbide inserts  112 . Located 180 degrees opposite are fixed inserts  114 , that are parallel to hardened inserts  112 , but at an angle with respect to whipstock axis  152 . There are return springs  116  on each piston  110 . The release system in  FIG. 5  works the same way as in  FIG. 4  in response to a remote signal to vent pressure and allow return springs  116  to retract the pistons  110 . As with  FIG. 4  the applied line  14  pressure trapped by the check valve  16  holds the set position. Any different amount of pistons  110  can be used and some can be articulated in a 180 degree opposed orientation. As before a retainer  42  limits the extension of the pistons when there is no surrounding tubular present. 
         [0028]      FIG. 6  is intended to show that cap  22  of  FIG. 1  can be removed at thread  24 . When that happens cone  32  can be converted to set down weight operation against hole bottom. Alternatively, a packer module  120  can be attached at thread  24  to in essence recreate chamber  20  for operation of cone  32  as in  FIG. 1  but to also extend a passage for hydraulic pressure to port  122  to drive piston  124  against seal assembly  126  and against fixed surface  128  so that slips  36  can be extended as well as a seal assembly  126 . A lock ring  130  holds the set of the seal assembly  126 . As before a tensile force on the whipstock  10  creates a tensile failure at necked down portion  60  to allow release of at least the slips  36 . 
         [0029]      FIG. 7  has a slightly different release system that acts to undermine the lock ring  44 . The layout is similar to  FIG. 4  with the difference being that actuation of plug  86  by system  90  based on a remote signal moves seal  88  past passage  96  to allow fluid in chamber  130  to reach lock ring  44  and undermine it with chemical attack or an equivalent way. 
         [0030]    Those skilled in the art will appreciate that the various design alternatives presented show a whipstock anchor that can be hydraulically set and can hold the set position with a check valve on the hydraulic line. Alternatively a lock ring can hold the set position and release occurs when a tensile force results in tensile failure of a mandrel to release the hydraulic pressure. Alternatively a release of hydraulic pressure can be remotely actuated with release of a retained plug whose movement vents hydraulic pressure or disables or undermines a lock ring chemically. A single piston can extend a slip with movement against a fixed surface or two pistons can be pushed in opposed directions. Movable slips can be oriented in opposition to each other or a movable slip can be opposite a fixed slip with inserts. Cocking of the whipstock can be accomplished by skewing the housing for the slips with respect to a whipstock axis or skewing the slip axis relative to an aligned whipstock and anchor housing axis. The designs feature simplicity in a hydraulically set anchor for a packer with a resultant economy in manufacturing. A removable cap can be used for hydraulic operation of a piston and with the cap removed for operating the piston with set down weight. A seal module can be secured in place of the end cap to allow setting a packer with the anchor and to release the anchor and the seal assembly when necked down portion  60  is broken. 
         [0031]    The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: