Abstract:
A torque anchor for use with progressive cavity pumps (PC Pumps) for preventing rotation of the PC Pumps and any related tool string within a well bore, possessing a connector constructed and adapted to connect a tube, which in a preferred embodiment is a diluent cable, between the two fixed slips. A method is also recited for running coiled tubing or a diluent cable downhole using the torque anchor.

Description:
FIELD OF THE INVENTION 
   The invention describes a torque anchor for use with progressive cavity pumps (PC pumps) for preventing rotation of the PC pumps and any related tool string and tubing within a wellbore. The torque anchor includes at least one fixed rigid slip and one pivotable slip that in combination enhance the ability of the torque anchor to remain centered within wellbore casing and provide space between the torque anchor and wellbore casing for other tubing and/or other cabling or instruments to be run within the well and/or facilitate the passage of sand and other substances indigenous to many well formations past the torque anchor. 
   BACKGROUND OF THE INVENTION 
   During oil-well production, in-line pumps such as progressive cavity pumps are used to pump oil from the well bore to the surface. A progressive cavity pump system includes a surface driven rotor mounted within a downhole stator that is rotationally secured to production casing so as to prevent rotation of the stator in response to the rotation of the rotor. The stator is secured to the production tubing by a torque anchor that permits the stator to be positioned in the well at a desired location wherein upon clockwise rotation of the tubing string and connected tool string, the torque anchor will lock against the wellbore casing and thereby secure the stator to prevent right-hand rotation of the tubing string within the well casing so as to enable operation of the progressive cavity pump. 
   Within a wellbore, it is often desired that in addition to enabling the operation of the progressive cavity pump, that one or more lengths of coiled tubing and/or cabling also be run within the wellbore to regions below the pump for various purposes such as to deliver hot oil or diluent to break up sand or heavy oil within the formation and/or to communicate with one or more instruments beneath the progressive cavity pump. That is, as operators seek to collect more information from a well during production and/or seek to concurrently perform other operations within the well using additional systems, auxiliary lengths of coiled tubing or cable may be run past the torque anchor. 
   In addition, in deviated wells in particular, it is desirable to maintain the progressive cavity pump in a centralized position to enable coiled tubing and/or cable to be readily run past the progressive cavity pump without binding or wedging of this auxiliary tubing or cabling between the torque anchor and casing or wellbore. 
   As a result, there has been a need for a torque anchor that, in addition to performing as an effective torque anchor, improves the ability of the operator to perform other operations within the well. Further, as progressive cavity pumps are often used in wells containing sand or other heavy substances it is desirable for the torque anchor to utilize a housing with as much flow-through space as possible, achievable by utilizing a housing with a smaller diameter and relatively larger slips. 
   A review of the prior art indicates that a number of different anti-rotation systems have been developed in the past that utilize a variety of concepts to provide different functionalities to an anti-rotation system or torque anchor. 
   For example, Advantage Products Inc. (Calgary, Alberta) produces a torque anchor that utilizes a single pivotable slip for deployment against well casing. In this system, the single slip extends from the main body of the torque anchor upon clockwise rotation of the tubing string such that when the slip engages with the well casing, the main body of the torque anchor is forced to move across the casing to the opposite side of the casing. This system can provide a pinch point that can damage tubing running adjacent to the torque anchor. In addition, this system by virtue of the main body of the torque anchor engaging with the well casing will similarly cause tools such as the stator of a PC pump to be biased against the well casing causing extra wear on such tools. 
   Canadian Patent 2,159,659 and U.S. Pat. No. 5,636,690 describe a torque anchor having pivotable slips for engagement with the well casing. In a horizontal and some deviated operations which make up a significant portion of all applications, a single slip engages and the main body of the torque anchor is pressed against the opposite side of the casing to the engaged slip. 
   Canadian Patent 2,220,392 describes a torque anchor having a plurality of drag slips that emerge from a slip cage and do not define a fixed volume of space between the slips. 
   Canadian Patent 2,238,910 describes a torque anchor to prevent right-hand rotation of tubing string within a stationary well casing. The system includes a fixed slip, two floating slips and a means for rotating the slips about the housing to create varying diameters of overall tool. 
   Canadian Patent 1,274,470 describes a no-turn tool having three movable slips that do not define a fixed volume between the slips. 
   Otatco Inc. (Calgary, Alberta) produces a torque anchor having a one piece body with integral slips and a collar to prevent right-hand rotation of a tubing string within a stationary well casing. The system includes a no-spring system having collars mounting passive dogs that provide anti-rotation when the collars are counter-rotated with respect to one another. 
   SUMMARY OF THE INVENTION 
   Accordingly, there is provided a torque anchor that improves on at least one prior art system. 
   More specifically, according to certain aspects of the invention, there is provided a torque anchor to prevent rotation of a tubing string within well casing so as to enable operation of a progressive cavity pump and to provide a definable volume of space between the torque anchor and well casing. According to a first aspect of the invention, there is provided a torque anchor to prevent rotation of a tubing string in a first direction while allowing rotation of the tubing string in an opposite second direction. The torque anchor includes a substantially cylindrical body shaped for insertion into a downhole casing of a wellbore; a moveable slip mounted on a periphery of the body, at least a portion of which is moveable outwardly from a central longitudinal axis of the body, wherein the moveable portion moves outwardly into operative contact with the downhole casing when the torque anchor is downhole and the tubing string is rotated in the first direction; at least two rigid slips fixedly coupled to the body, each longitudinally aligned with the longitudinal axis of the body and circumferentially spaced from one another and the moveable slip, the at least two rigid slips dimensioned to permit operative contact with the downhole casing when the torque anchor is downhole and the tubing string is rotated in the first direction; and attachment means for attaching a tube means, preferably a diluent cable, to the body between the at least two rigid slips, the attachment means dimensioned such that when the torque anchor is downhole, the attachment means and tube means are contained within a fixed volume of space defined by the body, the at least two rigid slips, and the downhole casing. 
   According to another aspect of the invention, there is provided a torque anchor to prevent rotation of a tubing string in a first direction while allowing rotation of the tubing string in an opposite second direction. The torque anchor includes a body shaped for attachment to a tubing string, the body supporting two rigid slips circumferentially spaced from one another at 75-120° to one another on the body for engagement with downhole casing or a well bore; an outwardly biased pivotable slip on the body circumferentially spaced from the at least two rigid slips wherein the pivotable slip is dimensioned to engage with the downhole casing or the well bore when the torque anchor is downhole and when the tubing string is rotated in the first direction, the body including a recess for receiving the pivotable slip when the pivotable slip is biased against the body; and attachment means for attaching a diluent cable to the body between the two rigid slips, the attachment means dimensioned such that when the torque anchor is downhole, the attachment means and diluent cable are contained within a fixed volume of space defined by the body, the two rigid slips, and the downhole casing or the well bore. 
   According to a further aspect of the invention, there is provided a method for running a tube downhole using a torque anchor configured to prevent rotation of a tubing string in a first direction while allowing rotation of the tubing string in an opposite second direction, and which includes a body shaped for attachment to the tubing string; an outwardly biased moveable slip on the body adapted to contact a downhole casing when the torque anchor is downhole and the tubing string is rotated in the first direction; at least two rigid slips circumferentially spaced from the moveable slip slips wherein the moveable slip is fixedly coupled to the body and dimensioned to operatively contact the downhole casing when the torque anchor is downhole, the at least two rigid slips circumferentially spaced from one another; and attachment means for attaching a diluent cable to the body between the at least two rigid slips, the attachment means dimensioned such that when the torque anchor is downhole, the attachment means and diluent cable are contained within a fixed volume of space defined by the body, the at least two rigid slips, and the downhole casing. The method includes attaching the torque anchor to the tubing string; attaching the tube (preferably a diluent cable) to the torque anchor; inserting the tubing string into a wellbore lined with the downhole casing; running the torque anchor downhole to a setting depth; and setting the torque anchor by applying torque to the tubing string in the first direction. 
   According to a further aspect of the invention, there is provided a method for running coiled tubing downhole using a torque configured to prevent rotation of a tubing string in a first direction while allowing rotation of the tubing string in an opposite second direction, and which includes a body shaped for attachment to a tubing string; at least one rigid slip fixedly coupled to the body and dimensioned to operatively contact with downhole casing when the torque anchor is downhole; and an outwardly biased pivotable slip on the body circumferentially spaced from the at least one rigid slip wherein the pivotable slip is dimensioned to operatively contact with the downhole casing when the torque anchor is downhole and the tubing string is rotated in the first direction. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described by the following detailed description and drawings wherein: 
       FIG. 1  is a side view of a torque anchor within casing in accordance with one embodiment of the invention; 
       FIG. 2  is a perspective view of a torque anchor within casing in accordance with one embodiment of the invention; 
       FIG. 3  is a view of a torque anchor within a well casing as viewed from below in accordance with one embodiment of the invention; 
       FIG. 3A  is a schematic side view of a pivotable slip of a torque anchor in accordance with one embodiment of the invention; 
       FIG. 3B  is a schematic end view of a mounting system for a pivotable slip of a torque anchor in accordance with one embodiment of the invention; 
       FIG. 4  is a view of a torque anchor centered within a well casing and showing auxiliary tubing as viewed from above in accordance with one embodiment of the invention; and, 
       FIG. 5  is a view of a torque anchor within a well casing and showing auxiliary tubing as viewed from above in accordance with one embodiment of the invention. 
   

   DETAILED DESCRIPTION 
   In accordance with the invention and with reference to the figures, embodiments of a torque anchor  10  are described. 
   With reference to  FIGS. 1-5 , embodiments of a torque anchor  10  are shown in two perspective views ( FIGS. 1 and 2 ) and cross-sectional views ( FIGS. 3 ,  4  and  5 ). The torque anchor generally includes a body  12  on which at least one rigid stabilizing slip, (preferably two)  14  and one outwardly biased and pivotable slip  16  are mounted. The body  12  includes appropriate male  18  and female  20  connectors to allow the torque anchor to be connected to a progressive cavity (PC) pump stator or tubing string (not shown) as known to those skilled in the art. 
   When mounted to a PC pump stator or tubing string, counter-clockwise rotation (as viewed from above) of the tubing string will permit counter-clockwise rotation of the torque anchor, PC pump and tubing string within well casing  22  (or well bore). Clockwise rotation of the tubing string (as viewed from above) will cause the pivotable slip  16  to engage with the well casing  22  such that the pivotable slip  16  and each of the rigid slips  14  are biased against the well casing  22  ( FIGS. 3 ,  4  and  5 ). As clockwise torque is maintained on the tubing string, the combination of the rigid slips  14  and pivotable slip  16  prevent clockwise rotation of the torque anchor  10  within the well casing. 
   As shown in  FIGS. 3 ,  4  and  5 , the rigid slips  14  and pivotable slip  16  create three distinct volumes A, B and C between the body and casing. Importantly, volume A is a fixed volume determined by the lateral dimensions and spacing of the fixed slips  14  whereas volumes B and C may vary depending on the inside dimensions of the well casing  22  and outside diameter of the body of the torque anchor  10 . Preferably, each of the rigid slips  14  and pivotable slip  16  are dimensioned so as to center the torque anchor body within the casing  22 .  FIG. 4  shows an embodiment where the slips  14  and  16  are dimensioned to center the tool whereas  FIG. 5  shows an embodiment where the body is not centered, but rather positioned to provide even larger volumes A, B and C. 
   As shown in  FIG. 4 , where the body is centered, there is a greater capacity to run coiled tubing  70  or diluent cable  71  past the torque anchor  10  within relatively symmetrical volumes B and C. As shown in  FIG. 5 , where the body is not centered as a result of a smaller lateral dimension of the pivotable slip  16  relative to the lateral dimension of the rigid slips  14 , volumes B and C are not symmetrical and, hence, may be able to accommodate different diameters of coiled tubing  70  and diluent cables  71  compared to the system shown in  FIG. 4 . 
   Also, as shown in  FIG. 4 , volume A may be utilized to rigidly attach the diluent cable  71  to the housing through a clamp system  30 . Alternatively, the same volume A may be utilized to loosely retain one or more lengths of coiled tubing  70  as shown in  FIG. 5 . 
   As shown to varying degrees in  FIGS. 3 ,  4  and  5 , the housing diameter may be different relative to the lateral dimension of the slip (as seen in cross-section) and/or the well casing  22  thereby providing different volumes A, B, C for flow of well fluid, sand or other material past the torque anchor  10 . 
   In a preferred embodiment, the rigid slips  14  are mounted on the body  12  parallel to the longitudinal axis of the body at approximately 90 degrees to one another as shown in  FIG. 3 . This angle may, however, be varied to approximately 75-120 degrees depending on the desired volume A. The rigid slips  14  are attached to the body through an appropriate connection system. It is preferred that the rigid slips  14  are attached using bolts to enable rigid slips  14  of different dimensions to be attached to the body so as to enable an operator to select the most appropriate dimensions for a given casing  22  and in order to create a desired fixed volume A. The rigid slips  14  may be set within a trough  32   a  ( FIG. 1 ) within the body to improve the structural strength of the torque anchor  10 . Alternatively, the rigid slips may be permanently fixed to the body by welding. The rigid slips  14  may be a single slip at each circumferential position on the body or may be separate pairs of slips longitudinally separated from one another (not shown). Each rigid slip  14  may be tapered along its upper  32  and lower edge  34  to facilitate vertical movement through the casing in either direction. 
   The outer surface  36  of the rigid slip  14  may be provided with an appropriate gripping surface to prevent slippage of the torque anchor  10  with respect to the casing  22  when the rigid slips  14  are engaged against the casing, such as a plurality of pointed and hardened ridges. As shown in  FIGS. 3 ,  4  and  5 , the pivotable slip  16  may also include a hardened pointed tip  16   g  (preferably tungsten carbide) to enhance the ability of the pivotable slip  16  to grip against casing  22 . 
   The pivotable slip  16  is pivotally mounted on the housing and is outwardly biased to ensure engagement of the pivotable slip  16  against the casing  22  during clockwise rotation of the torque anchor  10 . In the preferred embodiment, the pivotable slip  16  includes two mounting rods  16   a ,  16   b  ( FIG. 3A ) that are operatively retained within a corresponding mounting system such as lug  16   c  ( FIG. 3B ). The mounting system or lug includes a bore  16   d  for receiving a mounting rod  16   a ,  16   b . The mounting system or lug is attached to the body with appropriate bolts within bolt sleeves  16   e . As shown in  FIG. 2 , a torque anchor  10  may include two separate pivotable slips  16  longitudinally displaced relative to one another. The pivotable slips  16  may be also tapered along their upper and lower edges to facilitate vertical movement through the casing in either direction. 
   The pivotable slip  16  may be further attached in the manner as described in Canadian Patent 2,159,659 referred to therein as a pin-actuated slip. 
   The pivotable slip  16  may be further attached by a collar positioned circumferentially around and attached to the housing (not shown). 
   In other embodiments, the pivotable slip  16  may be pivotally retained within the body by other means such as but not limited to wedging or camming surfaces, and/or systems utilizing centrifugal force as known to those skilled in the art. 
   The body  12  may be further provided with a recess  50  to receive the pivotable slip  16  in a fully retracted position. 
   The pivotable slip  16  is also provided with at least one biasing spring to outwardly bias the pivotable slip  16 . The biasing spring is preferably a coil spring  60  (not shown) having a first end for operative contact with the body and a second end for operative contact with the pivotable slip  16 . The mounting system may include appropriate recesses such that that the coil spring is not exposed to the outer surfaces of the tool  10 . 
   The pivotable slip  16  may also be removed and an alternate dimension slip attached to the body so as to enable an operator to select the most appropriate dimensions for a given casing  20  and desired use. 
   Operation 
   In operation, the torque anchor  10  is threaded on a PC pump stator or on a tubing string above or below a PC pump. The pump and torque anchor  10  are run to the setting depth and torque is applied to the tubing string (right hand direction). The torque anchor  10  is released by rotation in the opposite direction (left hand direction). The torque anchor  10  can either be moved to a different location or pulled from the well. 
   The torque anchor  10  is an improvement over past torque anchors by providing superior centering capabilities of the PC pump and torque anchor over past torque anchors. As a result, and in combination with the operator&#39;s ability to attach rigid slips  14  and pivotable slips  16  of a particular dimension, a known volume of space can be created in a predictable location in a well of any orientation so as to enable auxiliary coiled tubing  70  and/or diluent cables  71  to be run adjacent to the torque anchor  10 . Further, the torque anchor  10  provides a generous amount of space for flow of well fluid materials such as sand, than other torque anchors do. 
   In addition, as contrasted with past torque anchors, the body of the torque anchor  10  can be made smaller than the PC pump stator as only the slips and not the body contact the well casing  22 . Also, the operation of the torque anchor  10  does not result in the biasing of the adjacent coiled tubing, diluent cables and tool string against the well bore which can result in extra wear to certain tools such as a PC pump. 
   Although the present invention has been described and illustrated with respect to preferred embodiments and preferred uses thereof, it is not to be so limited since modifications and changes can be made therein which are within the full, intended scope of the invention.