Abstract:
A drill pipe and casing protector comprises an annular body having two pieces with identical edges. A first edge includes at least two opposing formations longitudinally formed thereon whereby when one piece is inverted with respect to the either piece, the first edges mate to form a pivotable connection allowing the body to be opened and closed about a pipe. The second edges of each piece include opposing interlocks which form an aperture along the second edge when the body is closed. The aperture receives a locking pin to retain the body in a closed position around a drill pipe as well as around a bushing assembly.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a drill pipe and casing protector, and relates more particularly to a pivotable and lockable connection arrangement used with a protector for pipe and casing strings in the bore of a well. 
     2. Background of the Related Art 
     Pipe and casing protectors are well known. Their primary purpose is to prevent a string of drill pipe in a well from contacting the well bore or casing. In the drilling of oil and gas wells, a drill bit attached to the bottom of a drill string bores a hole into an underground formation. A drill string typically comprises a long string of connected tubular drill pipe sections that extend from the surface into a well bore formed by the drill bit on the bottom of the drill string. Casing is typically installed from the surface to various depths throughout the well bore to prevent the wall of the well bore from caving in and to prevent the transfer of fluids from various drilled formations from entering the well bore. The casing also provides a channel for recovering fluids if the well is productive. The terms “casing” and “well bore” will be used interchangeably herein. 
     During rotary drilling operations the drill pipe is subjected to radial and axial shock and abrasion whenever the moving drill pipe comes into contact with the wall of the well bore or the casing. In many drilling operations, the drill pipe may extend underground along a curved path, such as in deviated well drilling, and in these instances a considerable amount of torque can be produced by the effects of frictional forces developed between the rotating drill pipe and the casing or the wall of the well bore. Axial drag, brought about by contact between the pipe string and bore during the upwards and downwards movement of the pipe string is also a source of shock and abrasion. 
     In the past, drill pipe protectors have been placed in different locations along the length of a drill pipe to keep the drill pipe and its connections away from the walls of the casing. Typically, the protector comprises a generally annular body which surrounds but is free to rotate with respect to the drill pipe. Some prior art protectors are arranged and constructed to allow them to move freely in a longitudinal direction between the tool joints at the upper and lower ends of a pipe. Alternatively, annular retaining clamps may be applied to the pipe above and below the protector to restrict its range of longitudinal movement. The clamps may be positioned so as to locate the protector at a fixed position, or may be more widely spaced to allow longitudinal movement over a predetermined length of the pipe. 
     The outer diameter of the protector is greater than the maximum outer diameter of the joints connecting pieces of drill pipe and less than the inside diameter of the well bore or casing. The protector is preferably designed and constructed of materials that provide a relatively low coefficient of friction between the drill pipe and the inner surface of the protector and also between the outer surface of the protector and the bore or casing. In some cases, a bushing is affixed to the pipe and provides a low friction bearing surface upon which the inner surface of the annular body reacts. A number of protectors can be fitted to the pipe string and their location and number are typically determined by the relative likelihood contact between the pipe and casing wall in a particular well. Bidirectional wells for example, because of their non-linear path are particularly susceptible to pipe and casing wall contact both during rotation and during the insertion and removal of the drill string into the well. Protectors are therefore particularly useful in these wells. 
     In a typical arrangement, the protector body rotates with the drill pipe in the absence of contact between the protector and the casing. However, upon frictional contact between the body and the casing, the body stops rotating, or rotates very slowly, while allowing the drill pipe to continue rotating within the body unabated. This reduces rotational drag brought about by the contact between the rotating pipe string and the casing wall. Additionally, rollers are typically set into the body to reduce axial drag caused by the pipe moving up or down against the casing wall. 
     Improvements to protectors in recent years have included changes to the shape and configuration of the annular body and clamps, the use of bearing members on the internal and external surfaces of the annular body and between the body and the clamps or drill pipe joints, and materials for use in the fabrication of the body and bearings. In spite of recent improvements, some problems long associated with protectors still exist. For example, the protector, with its two piece annular body must be installed around a pipe which, in most cases already has a bushing and clamps installed around its perimeter. The installation of the annular body is accomplished by connecting the two pieces together at each side or at least at one side with pins, screws and bolts or plates and relying on a some type of hinge mechanism on the opposite side. This task can require special tools and extends the time that the well is not in operation. 
     There is a need therefore, for a pipe and casing protector that can be quickly and easily installed with a minimum of time and parts. 
     There is a further need for a protector which can be installed without the use of multiple fasteners and tools. 
     There is yet a further need for a protector which has a simple design making it easier to use and less expensive to manufacture. 
     SUMMARY OF THE INVENTION 
     The present invention generally provides a protector assembly that is quicker and easier to manufacture and install than those of the prior art. In one aspect of the invention, the protector includes an annular body with two pieces, each having identical edges. Male and female portions are formed along a first edge of each piece and opposing interlocks are formed along a second edge of each piece. When one piece is inverted with respect to the other piece, the male and female portions of the first edges mate to form a pivotable connection thereabout and the body can be closed around a pipe. As the body is closed, channels formed in each of the opposing interlocks align to form a longitudinal aperture constructed and arranged to receive a locking pin therethrough, thereby preventing the body from opening. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. 
     It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
     FIG. 1 is an exploded view showing the various pieces of a pipe and casing protector having the connection means of the current invention. 
     FIG. 2 is a perspective view showing the two-piece annular body. 
     FIG. 3 is a perspective view showing the position of the pieces as they are assembled together. 
     FIG. 4 is a perspective view showing the partially assembled two-piece annular body from the inside. 
     FIG. 5 is a perspective view showing the partially assembled two-piece annular body from the outside. 
     FIG. 6 is a perspective view showing the assembled, two piece annular body from the side of the pivotal connection. 
     FIG. 7 is a perspective view showing the assembled, two piece annular body from the side of the locking connection. 
     FIG. 8 is a top view showing the assembled two-piece annular body. 
     FIG. 9 is a perspective view of one side of the two-piece bushing assembly, the other side being identical thereto. 
     FIG. 10 is an exploded view showing a three piece clamp assembly. 
     FIG. 11 is an exploded view showing a two-piece clamp assembly. 
     FIG. 12 is a perspective view showing the assembled clamp and bushing assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is an exploded view of various pieces of a pipe and casing protector assembly having the connection arrangement of the present invention. The assembly includes an annular body made up of two identical pieces  100 , a bushing assembly made up of two identical pieces  310 , locking pin  250  and two clamp assemblies  400 . 
     Considering the components in greater detail, formed in each piece  100  are three bearing apertures  220 , each constructed and arranged to receive a pair of rollers  221  that aid the axial movement of the protector as it travels up and down in a casing or wellbore. More specifically, the rollers  221  interact with the casing wall to reduce axial drag between the pipe and the casing. A boss  223  is formed around each aperture  220  and each pair of rollers  221  are housed within boss  223  on axles (not shown) mounted through apertures  224  extending through each boss  223 . Each piece  100  also includes a tapered lip  112  formed at each end thereof to interact with clamp assembly  400  as will be described herein. 
     FIG. 2 is a perspective view of the two-piece annular body. The pieces  100  of the body are identical and are designed to be connected together along their edges  110  when one piece is held in an inverted position relative to the other piece, as they are depicted in FIG.  2 . Specifically, a pivotable connection is formed along first edge  110  of each piece and a locking connection is formed along second edge  150  of each piece. 
     In a preferred embodiment, first edge  110  of each piece  100  includes one female portion  115  and one male portion  120 . Female portion  115  has an outwardly directed, radiused channel  118  formed thereon. Male portion  120  includes an inwardly directed, radiused finger  119  formed thereon. Radiused channel  118  and radiused finger  119  are also visible in FIG.  8 . An assembly clearance  113  is formed along edge  110  between portions  115  and  120 . The opposite edge  150  of each piece  100  includes a number of opposing interlocks  135  aligned along the edge  150 , as best seen in FIG.  4 . In the preferred embodiment, each interlock  135  includes two planar surfaces  136  formed on each side of a longitudinal, semi-hemispherical channel  137  formed therebetween. 
     FIG. 3 depicts the two pieces  100  of the annular body and the relative position of each as they are assembled together. In order to form the pivotal connection along edges  110 , the two pieces  100  are rotated away from each other about a horizontal axis. FIG. 3 shows the pieces in such a relationship. With the assembly gaps  113  intersected as shown in FIG. 3, the pieces may be righted, causing radiused finger portion  119  of male portion  120  to be housed within the radiused channel  118  of female portion  115 . Once assembled, the pieces will pivot about the axis formed along finger  119  between an open and closed position. 
     FIG. 4 is a perspective view showing both annular body pieces  100  as they appear after having been connected together along their edges  110 . FIG. 4 depicts the body from the rear of the pivotal connection along edge  110 . Visible in FIG. 4 is assembly gap  113 , the inwardly directed radiused finger  119  of male portion  120  and outwardly directed radiused channel  118  of female portion  115 . Also visible in FIG. 4 are edges  150  with their opposing interlocks  135  which will form the locking connection around the drill pipe. As the body, which is pivotally connected about finger  119  along edges  110  is closed, inwardly and outwardly facing interlocks  135  align and the semi-hemispherical channels  137  formed in each interlock form an aperture  175  (not visible in FIG. 4) running the length of the edge  150 . Locking pin  250  (not shown) can then be inserted through the aperture locking the pieces together and preventing them from pivoting away from a closed position. 
     FIG. 5 is another perspective view showing the two pieces  100  of the annular body from the front of the pivotable connection about finger  119 , along edges  110 . Visible in the Figure are radiused channel  118  of the female portion  115  and inwardly directed, radiused finger  119  of male portion  120 . 
     FIG. 6 is a perspective view of the two piece annular body in an assembled state. Visible in FIG. 6 is that side of the annular body including edges  110  forming the pivotal connection between the two pieces  100  of annular body about finger  119 . FIG. 7 is another perspective view of the assembled, two piece annular body as seen from the side opposite the pivoting side and wherein the opposing interlocks  135  of each edge  150  are seen in an intersected relationship. Aperture  175 , formed by the semi-hemispherical channels  137  formed in each interlock  135 , is visible at the top of the annular body. The locking pin  250  is not installed. 
     FIG. 8 is a top view of the two piece annular body showing the relationship of both assembled body halves  100  as they appear from above. At the connection depicted at the left side of FIG. 8, edges  110  of each piece are mated with the radiused channel  118  of female portion  115  housing the inwardly directed, radiused finger  119  of male portion  120 . On the right side of the assembly, the lockable connection formed by the opposing interlocks about edges  150  is visible. Visible specifically are two of the semi-hemispherical surfaces  137  and four planar surfaces  136 , that form aperture  175 . While not depicted in FIG. 8, locking pin  250  may be inserted to prevent the annular body from opening at edges  150  and pivoting around the connection formed along edge  110 . 
     In a preferred embodiment, a bushing assembly is disposed between the two-piece annular body and drilling pipe. FIG. 9 shows one piece  310  of the two-piece bushing assembly. The other piece of the bushing assembly is identical to the piece  310  in FIG.  9  and both pieces are visible in FIG.  1 . As can be appreciated in FIG. 1, the interior  315  of the bushing assembly is formed to smoothly fit the outside diameter of a drilling pipe. As visible in FIG. 9, the exterior surface  318  of the bushing assembly is constructed to be disposed within the two piece annular body and to rotate independently thereof. The materials of the annular body and the bushing assembly are selected from those materials that offer the best wear characteristics as well as the lowest coefficient of friction between the moving parts. In the preferred embodiment, the body is constructed of high strength steel while the bushing is made of a high performance polymer material. Those skilled in the art will appreciate that a wide selection of individuals are available depending upon the needs of a customer and conditions of a particular well and the materials selected to manufacture the various parts of the assembly described herein can vary widely and remain within the scope of the invention and the claims of the patent. 
     FIG. 10 is an exploded view of a three piece clamp assembly  400  which is constructed and arranged to be assembled over drill pipe and the bushing assembly to hold the bushing assembly tight against the drill pipe and prevent its longitudinal or rotational movement with respect to the drill pipe. In the embodiment shown in FIG. 10, the clamp assembly consists of three pieces  401 ,  402 ,  403 , each having a castellated hinge  404  on at least one edge for interlocking that piece with the next piece of the clamp assembly  400 . Pins  405  act to hold the hinges together and a tightening screw  410  is provided to tighten the clamp assembly to a required torque around the bushing assembly and the pipe. 
     FIG. 11 is an alternative embodiment of a clamp assembly  402  and includes two pieces  455 ,  460  each of which has a tongue  465  formed along an edge  403  thereof and providing a hinge between the two pieces when they are fitted together. The opposite edge  404  of each piece includes an aperture  470 , the apertures aligning when the pieces are assembled together and closed. A locking pin  480  is used to lock and tighten the clamp around the bushing assembly and drill pipe. 
     FIG. 12 shows the arrangement by which the two-piece clamp assembly  402  is closed over the two piece bushing assembly to prevent the bushing assembly from rotating or moving longitudinally with respect to the drilling pipe. Specifically, a boss  315  formed on each end of the two piece bushing assembly is received into a mating cutout  320  formed at a first end of the assembled clamp  402 . A groove  325  formed around the perimeter of each end of the bushing assembly interacts with a mating formation in a first end of the clamp assembly. When the two pieces  100  of the annular body are assembled over the clamp/bushing assembly, lip  112  formed at each end of the pieces  100  fits against shoulder  327  formed at each end of the bushing assembly. 
     As described in the foregoing, in a preferred embodiment, the two piece annular body is made up of two identical pieces  100  which fit together when one is held in an inverted position relative to the other, to form a pivotable connection about a first edge of each piece  100 . The body can then be closed along an opposite edge  150  forming an aperture  175  into which a locking pin  250  may be inserted to lock the edges  150  and ensure the two piece annular body remains in a closed position on a drill pipe. As can be appreciated in FIG. 4, when the pieces  100  are joined along the leading edge  110 , the partially assembled body can then be easily placed longitudinally over a piece of drilling pipe prior to being closed about edges  150  and locked shut over a bushing assembly along edges  150  with pin  250 . 
     While foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.