Abstract:
Disclosed is a rotating tool for inducing rotation, e.g., for activating and operating coil tubing tools for fishing target equipment in a bore casing of an oil well-bore. The rotating tool is connected with an end of coiled tubing reeled into the oil well-bore, and its other end is connected to a target equipment on which rotation is to be induced. The rotating tool converts linear motion in a first direction of the coiled tubing into rotation, and the rotation hence produced operates a coil tubing tool e.g., opening/closing jaws on an overshot. The rotating tool includes adjustable screws which allow the rotation resistance to be adjusted.

Description:
FIELD OF INVENTION 
       [0001]    This invention relates to rotating tools for generating rotation to use with equipment installed within a bore casing of an oil well-bore, especially for coil-tubing applications. 
       BACKGROUND 
       [0002]    Oil wells are generally formed by drilling a bore into the earth for accessing buried crude oil deposits, and then installing a variety of equipment within the bore to enable pumping of crude oil up to the earth&#39;s surface. During drilling, hollow metallic tubes (also known as ‘casings’) are inserted within the bore to prevent walls of bore from collapsing. In a deep enough bore, multiple hollow casings are installed vertically one above the other by screwing ends of adjacent sections with each other. The entire assembly of attached casings is commonly known as ‘bore casing’. 
         [0003]    Once a bore casing is formed, a variety of equipment (including crude oil pumping equipment and sensor equipment) is installed within the bore casing. In an operational oil well, crude oil is pumped to the surface of the earth from the buried crude oil deposits with the help of pumping equipment installed in the bore casing. However, the oil well production unit is vulnerable to failure of installed equipment within the bore casing, which can be caused by mechanical fatigue or electrical shorts or other problems, which can be exacerbated by changed conditions within the well-bore. 
         [0004]    During installation of pumping equipment, or during troubleshooting of failed equipment in an operational oil well-bore, it is often necessary to retrieve equipment from the bore casing (also known as fishing). Retrieval of equipment which may be imperfectly installed or lie stuck within the bore casing, can be accomplished by grasping it with an overshot tool (having jaws) connected to the coiled tubing. Jaws of an overshot are generally opened and closed by rotation provided to the overshot. Additionally, rotation provided by the overshot can help to set free stuck equipment. Since the coil tubing cannot be rotated easily—but it can be moved up and down linearly from a drum powered by a drive motor, a mechanical transfer of linear motion of the coil tubing into rotational motion is required. 
         [0005]    A rotating tool can be used in a well-bore with coil tubing in conjunction with a drilling jar. See e.g. U.S. Pat. No. 8,151,910 (incorporated by reference). While the drilling jar generates impacts and resultant shock waves along the coil tubing to aid in freeing the tubing or stuck equipment, the rotating tool generates rotation for the overshot and rotation for freeing the stuck equipment. The current designs of rotating tools do not work well with the hard accelerations needed to be applied to the coil tubing (it must be jerked up or down, or both) to generate the jarring effect. The current designs tend to rotate too freely, which can cause tools designed to operate when rotated to be unintentionally activated. The rotating tool described below solves these problems with the existing rotating tools. 
       SUMMARY 
       [0006]    The invention is a rotating tool for inducing rotation. When included in coiled tubing of an oil well-bore, the rotating tool of the present invention is useful for operating or freeing target equipment within the bore casing of an oil well-bore. One end of the rotating tool is connected with an end of coiled tubing reeled into the oil well-bore, and its other end is connected to target equipment on which rotation is to be induced. The rotating tool converts linear motion (up or down) of the coiled tubing into rotation. The rotation hence produced is used to operate the target equipment; e.g., opening/closing jaws on an overshot. 
         [0007]    In a rotating tool, a sliding assembly, including a shaft, slides within a housing assembly. Linear displacement of the shaft in one direction is converted into rotational motion in a first rotational direction through a tubular gear, which in turn induces rotation of the housing assembly and the target equipment in the first rotational direction. 
         [0008]    The housing assembly includes a upper-sub, a barrel, a lower-sub and a first longitudinal bore. A mandrel of the sliding assembly is connected to the coiled tubing and is used to drive the shaft linearly through the first longitudinal bore. The upper-sub is screwed to one end of the barrel, the lower-sub is screwed to the opposite end of the barrel, and the distal end of the lower-sub is connected to the target equipment. The proximal end of the lower-sub includes a first set of axially-extending gear teeth. 
         [0009]    The surface of the shaft includes axially-extending helical grooves. The tubular gear surrounds the grooved surface of the shaft and engages with the helical grooves through one or more adjustable screws which extend transversely through threaded holes in the tubular gear. Adjusting the extent to which the adjustable screws extend into the grooves can be used to exert varying degrees of pressure by the adjustable screws on the bottom of the grooves, and thereby varying the force required to make the tubular gear travel along the helical grooves (and the shaft). One end of the tubular gear includes a second set of multiple axially-extending gear teeth which mate with the corresponding first set of axially-extending gear teeth of the lower-sub, but permit rotation in one direction only. 
         [0010]    Within the rotating tool, axial movement of the tubular gear is prevented beyond longitudinal separation between the lower-sub and a tubular head of the shaft. When the shaft is moved axially in a first linear direction and when the tubular gear is pushed against the lower-sub, the adjustable screws of the tubular gear slide along the helical grooves and cause the tubular gear to rotate in a first rotational direction. Since the second set of gear teeth of the tubular gear matingly engage with the first set of gear teeth of the lower-sub, rotation of the tubular gear also causes the lower-sub to rotate in the first rotational direction. And the rotation of the lower-sub also causes the entire housing assembly and the target equipment to rotate in the first rotational direction. 
         [0011]    As described further below, the adjustment of the screws facilitates fishing operations where equipment is stuck and must be dislodged by activating a jar. Embodiments of the present invention will be discussed in greater details with reference to the accompanying figures in the detailed description which follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1A  is a cross-sectional view of a first embodiment of a rotating tool. 
           [0013]      FIG. 1B  is an expanded cross-sectional view of the portion of  FIG. 1A  shown as expanded by the lead lines. 
           [0014]      FIG. 2A  illustrates a cross-sectional view of a tubular gear used in the first embodiment. 
           [0015]      FIG. 2B  is an elevational view of the tubular gear. 
           [0016]      FIG. 3  is a perspective view illustrating engagement of the shaft and the tubular gear in the first embodiment. 
           [0017]      FIG. 4  is an elevational view of the lower-sub. 
           [0018]      FIG. 5  is an elevational view of the lower-sub engaged with the tubular gear. 
           [0019]      FIG. 6A  is a cross-sectional view of the rotational tool in a “ready for down-stroke” position. 
           [0020]      FIG. 6B  is a cross-sectional view of the rotational tool in a “ready for up-stroke” position. 
           [0021]      FIG. 7  illustrates a coil tubing set up for fishing including a rotating tool of the present invention and a drilling jar. 
       
    
    
       [0022]    It should be understood that the drawings and the associated descriptions below are intended and provided to illustrate one or more embodiments of the present invention, and not to limit the scope of the invention. Also, it should be noted that the drawings are not be necessarily drawn to scale. 
       DETAILED DESCRIPTION 
       [0023]    Reference will now be made in detail to a first embodiment of a rotating tool of the invention with reference to the accompanying  FIGS. 1A to 6B . As illustrated in these figures, rotating tool  100  comprises a mandrel  102 , an upper-sub  104 , a barrel  106 , a shaft  108 , a tubular gear  110 , a piston  112  and a lower-sub  114 . The mandrel  102 , the shaft  104 , and the piston  112  together form a longitudinal sliding assembly which is slideable within a housing assembly formed by the upper-sub  104 , the barrel  106 , and the lower-sub  114 . To form the housing assembly, internally threaded portion  116  and  118  of the barrel  106  are screwed on to the upper-sub  104 , and the lower-sub  114  respectively. Each of the upper-sub  104 , the barrel  106 , and the lower-sub  114  include a longitudinal cylindrical bore, and all three bores are aligned along a longitudinal axis of the barrel assembly so as to provide a passage for the sliding assembly to slide through. In  FIG. 1A , the passage for sliding assembly to slide within the lower barrel is illustrated as path  122 . 
         [0024]    Mandrel  102  includes sliding cylinder  124 , an outer cylinder  126  and a longitudinal bore  128  extending through the sliding cylinder  124  and the outer cylinder  126 . A portion of the longitudinal bore  128  which lies in the outer cylinder  126  widens towards end  130  of the outer cylinder  126  and is internally threaded for connecting the rotating tool  100  to coiled tubing (shown in  FIG. 7 ). 
         [0025]    Shaft  108  comprises of a tubular head  132 , an externally grooved cylindrical region  134  and a longitudinal bore  136  extending through the head  132  and threaded cylindrical region  134 . Portion of the sliding cylinder  124  which lies proximate to its end  138  is externally threaded (shown as externally threaded portion  140  in  FIG. 1A ). The externally threaded portion  140  is screwed into one end of the tubular head  132  of shaft  108 . Piston  112  is a tubular cylinder and includes a longitudinal bore  142 . Portion of the shaft  108  which lies proximate to its end  120  is externally threaded and is screwed into one end of the piston  112 . 
         [0026]    Tubular gear  110  surrounds a portion of the grooved cylindrical region  134  and is engaged to its grooves  153  through adjustable screws  144  as best seen in  FIG. 1B  and  FIG. 3 . Depth of engagement of ball  145  at the tip of screw screws  144  in grooves  153  of grooved cylindrical region  134  can be adjusted by rotating the screws in or out through their corresponding threaded holes  146  in tubular gear  110 . Ball  145  is optional at the tip of screws  144 , and no ball or other types of interfaces with the grooves  153  are within the scope of the invention. A magnified view of engagement of tubular gear  110  with grooves  153  of grooved cylindrical region  134  is also illustrated in  FIG. 1B . A compressible helical spring  148  surrounds threaded cylindrical region  134 , as best seen in  FIG. 3 . Longitudinal extension of spring  148  is restricted to within of the linear edges of a dynamic region  150 , which is bounded by the barrel  106 , the externally helically grooved region  134 , the tubular head  132 , and the tubular gear  110 . 
         [0027]    The lower-sub  114  further includes a first set of multiple axially-extending gear teeth  152  (as best seen in  FIG. 4 ), an externally threaded tapered arm  154 , an additional reduced diameter bore  156  connected to path  122  (as best seen in  FIGS. 1A, 6A and 6B ). In an installed coiled tubing assembly, the tapered arm  154  is preferably screwed into to a mating lower portion of the coiled tubing which extends into the oil well-bore, or directly connected with a fishing tool (such as an overshot) as described below and shown in  FIG. 7 . In a coiled tubing assembly having the rotating tool  100  installed, bore  128 , bore  136 , bore  142 , path  122 , and bore  156  together provide a fluid flow path for a fluid (flowing along the coil tubing) to pass through rotating tool  100 . 
         [0028]      FIGS. 2A and 2B  illustrates structure of tubular gear  110  in greater detail. Tubular gear  110  includes two holes  146  and a second set of multiple axially-extending gear teeth  158 . Holes  146  are internally threaded to allow screwing or unscrewing of the threaded portion of screw  144  through them. When fully screwed in, ball  145  at the tip of screws  144  can engage with the lower portion of grooves  153  of threaded cylindrical region  134 . 
         [0029]    To prevent leakage of fluid flowing through the rotating tool  100  (for example, drilling fluid flowing through the coiled tubing) into the dynamic region  150  through the interface between the piston  112  and path  122 , rubber O-rings  160  are provided around piston  112  (illustrated in  FIG. 1  and  FIG. 3 ). A detailed perspective view of the assembly of the shaft  108 , the spring  148 , the tubular gear  110  (cross-sectional view), and the piston  112  with O-rings  160  as installed in rotating tool  100  is shown in  FIG. 3 . 
         [0030]    As shown in  FIG. 5 , the second set of gear teeth  158  of the tubular gear  110  matingly fits into the first set of gear teeth  152  of the lower-sub  114 . In such a mated assembly, rotation of tubular gear  110  (as it travels down the helical groove in shaft  108 ) would also cause the lower-sub  114  to rotate in same rotational direction. 
         [0031]    Operation of the rotating tool  100  for producing rotation during down-stroke will now be explained in detail with reference to  FIGS. 6A-6B . As illustrated in  FIG. 6A , to initiate a down-stroke, the mandrel  102  is pushed down into the housing assembly through the upper-sub  104  by reeling out coil tubing  702  from drum  704  (as illustrated in  FIG. 7 ). As sliding cylinder  124  is pushed in by this action, the shaft  108  (along with the piston  112 ) gets pushed into path  122 . Since tubular gear  110  is engaged with grooves  153  of the shaft  108  through screws  144 , axial force is also exerted on the tubular gear  110 . Since axial movement of the tubular gear  110  is prevented beyond the lower-sub  114 , the exerted force causes engaged tips of screws  114  to slide through the helical grooves  153  of the shaft  108 . Sliding of screws  114  through helical grooves  153  of shaft  108  causes the tubular gear  110  to rotate in a first rotational direction (for example, in clockwise direction in the present embodiment). Since gear teeth  158  of the tubular gear  110  are matingly engaged with gear teeth  152  of the lower-sub  114 , rotation of tubular gear  110  also causes the lower-sub  114  to rotate in a first rotational direction. Still further, since the lower-sub  114  connected with the barrel  106 , rotation of lower-sub  114  further causes the entire housing assembly to rotate in the first rotational direction. As a result of rotation, tubular gear  110  (through screws  144 ) also moves up the groove towards the tubular head  132 . Finally, when the entire length of sliding cylinder  124  is moved into the housing assembly (as illustrated in  FIG. 6B ), the down-stroke concludes, and the tubular gear  110  sits closer to the tubular head  132 . Further, the spring  148  lies compressed between the tubular head  132  and the tubular gear  110 . 
         [0032]    During up-stroke, the pushing force on mandrel  102  is released and a pulling force is applied on mandrel  102  (and to the shaft  108 ) by reeling in coil tubing  702  from drum  704  (as illustrated in  FIG. 7 ). When the shaft  108  is pulled out, linear movement of the tubular gear  110  towards the upper-sub  104  is opposed by the spring  148 , but the spring  148  now gradually begins to uncompress into the additional availability of space in dynamic region  150 . Pressure released from uncompressing spring  148  forces tubular gear  110  towards lower-sub  114 . As a result of force exerted by the uncompressing spring, the screws  144  of the tubular gear  110  start to sliding in a reverse direction along the grooves  153  of the shaft  108 . Such a sliding causes the tubular gear  110  to rotate in a counter-clockwise direction (i.e. opposite to rotational direction during the down-stroke). However, due to structure and mating profile of gear teeth  152  and  158 , rotation of tubular gear  110  in counter-clockwise direction does not induce any rotation on the lower-sub  114  (and hence in the housing assembly). During up-stroke, teeth  158  simply slidingly rotate over the mated gear teeth  152  (the teeth  158  and  154  only lockingly engage in one rotational direction). 
         [0033]    The sensitivity of rotating tool  100  to produce desired a desired amount of rotation per unit of pushing force on the mandrel  102  during down-stroke can be adjusted by the degree of engagement of screws  144  with the grooves  153  of the shaft  108 . Pressure exerted by screws  144  at the bottom of the grooves  153  can be adjusted. Higher friction between the tips of the screws  144  and grooves  153  of the shaft  108 , would result in lesser rotation of tubular gear  110  per unit force applied on mandrel  102 . To achieve larger amount of rotation per unit of pushing force, friction between screws  144  and grooves  153  of shaft  108  should be reduced, and screws  144  should not be driven to an extent that their respective tips become tightly engaged with the grooves  153  of the shaft  108 . 
         [0034]    When screws  144  is driven in through the hole  146 , ball  145  at the tip of screw  144  engages firmly with the groove of the shaft  108 . Driving the screw  144  deeper into hole  146  would push the metallic ball  145  tightly against the groove of shaft  108 , and hence the ball  145  would engage with a greater pressure and friction with the groove of shaft  108 . Hence, positioning of screw  144  within hole  146  can be used to adjust the magnitude of pressure exerted by the metallic ball  145  on the grooves  153  of shaft  108 . In other words, level of engagement of tubular gear with grooves  153  of the shaft  108  can be adjusted by driving the screw  144  suitably within hole  146 . The structure and dimensions of hole  146 , screw  144  and the metallic ball  145  can be chosen suitably to ensure that while being engaged with the groove of the shaft  108 , the ball  145  remains engaged with the hole  146  too, and that driving of screw  144  into hole  146 , or any rotation of tubular gear  110  around the shaft  108  does not result in losing the engagement of metallic ball  145  with the hole  146 . As an example, to ensure that driving of screw  144  into hole  146  does not result in losing the engagement of metallic ball  145  with the hole  146 , the hole may be constructed in a manner such that driving the screw  144  into the hole  146  is restricted beyond a threshold. 
         [0035]      FIG. 7  shows the assembly of coil tubing  702 , reeled from a drum  704  by a drive motor  710  and an injector  712  in an oil well-bore casing  706 . The coil tubing  702  is connected with a drilling jar  708  and with a rotating tool  100 , which drives an overshot  700  having jaws  716 . To retrieve a target equipment  714  from a well bore, the coil tubing  702  is reeled down from the drum by a drum  704  by a drive motor  710  and an injector  712 . To avoid dislodging the equipment  714  and having it fall down the well bore, lowering of coil tubing  702  slows as it nears the equipment  714 . At the time of contact between the distal end of the overshot  700  and the equipment  714 , lowering is immediately stopped. The adjustable screws  144  in the rotating tool  100  have been set so that there is little friction between them and the helical grooves  153  of shaft  108 , and rotation of the lower-sub  114  (or the housing assembly) and the overshot  700  is induced by relatively modest downward acceleration of the assembly of coiled tubing  702  by the motor  710 . The rotation closes the jaws  716  of the overshot on the equipment  714  so that the equipment  714  is grasped by jaws  716 . Finally, the assembly of coiled tubing  702  is reeled up (carrying up the equipment  714  grasped in jaws  716 ). 
         [0036]    In the event the equipment  714  is lodged or stuck in the well bore and needs to be freed by activating the jar  708 , the assembly of coiled tubing  702  must be rapidly accelerated up or down to induce a jarring impact. Additionally, where it is known that equipment  714  is stuck firmly, one can tighten screws  144  before lowering the assembly of coiled tubing  702 , and then contact the stuck equipment  714  with a solid impact on it by the overshot  700 , before activating the overshot jaws  716  to close, using another strong downward force (which may help dislodge the stuck equipment  714 ). 
         [0037]    Alternatively, the first try to grasp and release stuck equipment  714  can be done with the screws  144  in a loosened setting, so the equipment  714  is not accidentally dislodged. The jaws  716  are then closed with a downward force on the assembly of coil tubing  702 . If attempts to release the equipment  714  fail, with or without firing the jar  708 , the jaws  716  can be opened by applying another rotational force through the rotating tool  100  by pushing the mandrel  102  downwardly again (following an up-stroke of it). The assembly of coil tubing  702  can then be reeled up to the surface without the equipment  714 , the screws  144  tightened, and then lowered again so that overshot  700  impacts the stuck equipment  714 , before grasping it again with jaws  716  and firing the jar  708  again, if necessary. The impact of the overshot  700  may be enough to help free the equipment  714 . 
         [0038]    In different embodiments the pitch of the grooves  153  on shaft  108  can be varied, so as to reach a specified degree of rotation for each operating cycle of a rotating tool  100 , i.e., one full downstroke or upstroke of mandrel  102 . In operations where after grasping equipment  714 , jar  708  is activated to file bi-directionally several times to aid in dislodging the stuck equipment  714 , the pitch on grooves  153  can still allow control of the grasp strength of the jaws  716 . For example, first the equipment  714  is grasped with a grip strength sufficient to lift it, but not significantly more—in the event equipment  714  has components which could be damaged by an over-strength grasp by jaws  716 . Then, if the equipment  714  cannot readily be lifted by reeling drum  704  up, one would activate the drilling jar  708 . Assuming that three cycles of activating the jar  708  bi-directionally (where it fires six times in total) would power a calibrated overshot  700  to exert a force increase between 1,000-50,000 psi at its jaws  716 , such increase would then be applied by jaws  716  on the equipment  714 —before one again attempts to lift it. This feature avoids the risk of damaging equipment in the event the overshot&#39;s  700  grip strength at its jaws  716  is not calibrated, and if the number of activations of jar  708  is not controlled. 
         [0039]    Various other types of fishing tools and coil tubing set-ups can also be used in an oil well-bore. It is to be understood that the foregoing description and embodiments are intended to merely illustrate and not limit the scope of the invention. Other embodiments, modifications, variations and equivalents of the invention are apparent to those skilled in the art and are also within the scope of the invention, which is only described and limited in the claims which follow, and not elsewhere.