Abstract:
Apparatus and methods, for making and breaking connections in a horizontal boring drillstring, comprising a skid-mounted torque wrench and a spinning unit hydraulically operated from a remote control station, therefore allowing a coupling to be made or broken without manual intervention. One embodiment of a preferred torque wrench and spinning unit is horizontally mounted on a structural frame that is adapted to allow movement relative to a horizontal drill string. A preferred torque wrench comprises a gripping mechanism that serves to hold stationary one half of a coupling and a torquing mechanism that arcuately translates the adjoining half of the coupling to either make-up or break-out the coupling. A preferred spinning unit comprises a plurality of drive rollers that impart rotational motion into the pipe to engage or disengage the threads of a coupling.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application claims the benefit of 35 U.S.C. 111(b) provisional application Serial No. 60/349,008 filed Jan. 14, 2002, and entitled Horizontal Boring Pipe Connecting and Disconnecting Device. 
     
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not applicable.  
         FIELD OF THE INVENTION  
         [0003]    This invention relates generally to underground boring. More particularly, this invention relates to methods and apparatus for making and breaking threaded connections between pipe segments that are used in underground boring. Still more particularly, the present invention relates to making and breaking threaded connections at the pipe end of a horizontal borehole.  
         BACKGROUND OF THE INVENTION  
         [0004]    Utility lines for water, electricity, gas, telephone and cable television are often run underground for reasons of safety and aesthetics. In many situations, the underground utilities can be buried in a trench which is then back-filled. Although useful in areas of new construction, the burial of utilities in a trench in developed areas may result in disturbance to existing structures, roadways, and utilities. As a partial solution, the general technique of boring a horizontal underground hole has been developed in order to overcome some of the disadvantages of conventional trenching techniques.  
           [0005]    In accordance with such a general horizontal boring technique, also known as microtunnelling, horizontal directional drilling (HDD) or trenchless underground boring, a boring system is situated on the ground surface and drills a hole into the ground at an oblique angle with respect to the ground surface. The hole is normally drilled by rotating a drill bit that is attached to the end of a length of hollow pipe. As the depth and length of the hole increases, additional lengths of pipe are attached and fed into the hole. The assembly of the multiple lengths of pipe and the drill bit is known as a drill string. A drilling fluid is typically flowed through the drill string, over the bit, and back up the borehole in order to remove cuttings and dirt.  
           [0006]    After the drill reaches a desired depth, the tool is then directed along a substantially horizontal path to create a horizontal borehole. Once the desired horizontal borehole is drilled, the drill string then drills through to the surface. The location at which the pipe breaks the surface is referred to as the “pipe end” of the hole, while the end from which the hole is drilled is known as the “drill end.” At the pipe end, a reamer may be attached to the drill string and pulled back through the borehole, thus reaming out the borehole to a larger diameter. It is also common to attach a utility line or other conduit to the reaming tool so that it is dragged through the borehole along with the reamer. When installing a reamer, or for other applications, it is sometimes desirable to be able to break-out individual lengths of drill pipe from the pipe end of the hole.  
           [0007]    Drill strings may comprise many individual lengths of pipe, each of which is connected in series to form the drill string. The joints between lengths of pipe are often threaded connections that must be torqued to within set limits in order to prevent failure of the connection or damage to the thread. In most prior art boring applications, the individual lengths of pipe are positioned in place and connected to the drill sting manually. Manually making and breaking these pipe connections not only takes a long time but is potentially hazardous to personnel using the equipment.  
           [0008]    In vertical drilling applications, such as those used to drill hydrocarbon wells, this safety and efficiency problem has been addressed by mechanisms designed to connect and disconnect lengths of vertical drill pipe. One such mechanism is disclosed in U.S. Pat. No. 4,348,920, issued to Boyadjieff. Boyadjieff discloses is what has become known as an iron roughneck, or automatic roughneck. These devices generally comprise a large structure mounted on rails that allow the structure to move from a remote position to a position centered on a drill string. Once a new length of drill pipe is placed in position over the drill string, the iron roughneck is moved into position. An iron roughneck generally comprises a spinning mechanism that grasps the new drill pipe and rotates it until the connection is initially made-up. Iron roughnecks also have a torquing mechanism that imparts the required amount of torque into the threaded connection. Most iron roughnecks can also be used to disconnect the lengths of drill pipe.  
           [0009]    Horizontal drilling units, such as are described in U.S. Pat. No. 5,231,899, issued to Lee, also have been designed with components that are used to make-up and break-out lengths of drill pipe from the drill end of the hole. Lee describes a rotary drill rig, mounted on a frame and having a moveable carriage with a rotary motor. The rig also has one wrench for holding pipe in place and second wrench fitted with a hydraulic cylinder for applying torque to make or break connections. As new pipe joints are added or removed, the wrenches are used to make or break the connections and the rotary motor, which also provides drilling torque, engages or disengages the connection threads.  
           [0010]    There are no devices currently being used to automate the process of connecting and disconnecting lengths of pipe used in horizontal boring operations at the pipe end of the hole. Therefore, there remains a need in the art to develop a device which will make and break threaded connections used in these types of operations. The present invention is directed to methods and apparatus for making and breaking connections between pipes used in horizontal boring operations.  
         SUMMARY OF THE PREFERRED EMBODIMENTS  
         [0011]    Accordingly, there is provided herein methods and apparatus for making and breaking connections in a drillstring used in horizontal boring operations. One embodiment of the present invention comprises a torque wrench and a spinning unit that operate to fully engage and disengage a coupling in a horizontal drill string. A preferred torque wrench and spinning unit is hydraulically operated from a remote control station, therefore allowing a coupling to be made or broken without manual intervention.  
           [0012]    One embodiment of a preferred torque wrench and spinning unit is horizontally mounted on a structural frame that is adapted to allow movement relative to a horizontal, or near horizontal, drill string. A preferred torque wrench comprises a stationary gripping mechanism and a rotating torquing mechanism, wherein the gripping mechanism serves to hold stationary one half of a coupling while the torquing mechanism arcuately translates the adjoining half of the coupling to either make-up or break-out the coupling. A preferred spinning unit comprises a plurality of drive rollers that impart rotational motion into the pipe in order to engage or disengage the threads of a coupling. Both the torquing mechanism and the spinning unit preferably are adapted to receive pipe sections either along the axis of the drill string or in a direction perpendicular to that axis.  
           [0013]    In one preferred method of operation, the torquing mechanism and spinning unit are opened to accept the end of the drill string. The gripping portion of the torquing mechanism grasps the drill string on the coupling to be broken. The torquing mechanism is then actuated until the coupling begins to turn. The gripping and torquing mechanisms are then released and the spinning unit is activated in order to disengage the threaded coupling of the pipe joint from the mating coupling on the drill string. The spinning unit rotates the pipe joint about the axis of the coupling until the thread is fully disengaged. Once the thread is fully disengaged, the pipe joint can be removed and stored until needed. All of the above described steps are preferably executed without manual intervention in the torquing or spinning process. The operation can be controlled from a remote control station. The above described method can also be used to makeup a pipe joint by reversing the process.  
           [0014]    Thus, the present invention comprises a combination of methods and apparatus that enable a pipe joint to be made-up or broken-out of a horizontal drill string without manual intervention from an operator. Thus, the present invention increases safety by removing personnel from the process and improves the process by providing a consistent level of torque applied to the couplings. These and various other characteristics and advantages of the present invention will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments of the invention and by referring to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    For a more detailed understanding of the preferred embodiments, reference is made to the accompanying Figures, wherein:  
         [0016]    [0016]FIG. 1 is an elevation view of one embodiment of a combination torque wrench and spinner assembly;  
         [0017]    [0017]FIG. 2 is an elevation view of one embodiment of a torque unit;  
         [0018]    [0018]FIG. 3 is an elevation view of one embodiment of a torque unit; and  
         [0019]    [0019]FIG. 4 is an elevation view of one embodiment of a spinner unit. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawing figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness.  
         [0021]    The present invention relates to methods and apparatus for making and breaking pipe couplings in a horizontal drill string. The present invention is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present invention with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein. In particular, the following description of a method of employment will involve using embodiments of the present invention to remove joints of pipe from the drill string at the pipe end of the hole, but the embodiments of the present invention can also be used to add lengths of pipe at the drill end. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce desired results.  
         [0022]    Referring now to FIG. 1, an elevation of an assembly  10  comprises a torque unit  14  and a spinning unit  16 , each of which are slidably mounted to a skid  12 . Skid  12  has a rails  30 ,  32  on which torque unit  14  and spinning unit  16  are slidably engaged. Torque unit  14  can be moved along rails  30  by extending or retracting hydraulic cylinder  26 . Spinning unit  16  can be moved along rails  30  by extending or retracting hydraulic cylinder  28 . Wheels  34 , attached to torque unit  14  and spinning unit  16  on rails  30 .  
         [0023]    Torque unit  14  is preferably capable of imparting a required torque into a coupling, either to make or break the connection. Torque unit  14  is preferably mounted to a chassis  18  that supports the unit and provides for lateral movement in relation to skid  12 . This movement allows torque unit  16  to be adjusted to properly align with a coupling. Torque unit  16  is also preferably capable of acting in a clockwise or counter-clockwise direction. A preferred torque unit  16  is actuated and controlled by a hydraulic system.  
         [0024]    [0024]FIG. 2 generally illustrates the structure of one embodiment of a torque unit  14  including a rotating gripping assembly  22  adapted to grip and apply torque in either direction to one half of a pipe coupling, and a stationary gripping assembly  20  adapted to engage and maintain stationary the other half of a coupling. Each gripping assembly  20 ,  22  comprises gate  54  pivoted to body  64  for movement between an open position passing the pipe into engagement with the gripping assembly and a closed position to securely grip the pipe within the assembly. Gate  54  may be held in closed position by a latch element (not shown) and is preferably moved between the open and closed position by hydraulic actuators (not shown). Once gate  54  is closed, gripping elements  66 , carried by gate  54 , and diametrically opposed gripping elements  68 , mounted to piston  56 , act to tightly grip the pipe when pressurized fluid is forced into a cylinder chamber (not shown) to move piston  56  toward the center of pipe  40 .  
         [0025]    As shown in FIG. 3, after first and second gripping assemblies  20 ,  22  have been actuated to tightly grip pipe  40  on either side of a threaded connection, the assembly  22  is rotated relative to pipe  40  and assembly  20  to either break the threaded connection or make it up to a tightened condition. This relative rotation is produced by two piston and cylinder mechanisms  58 , each of which has its cylinder connected to one of assemblies  20 ,  22  by a pivoting arm  60 ,  62 . The pressure acting on piston and cylinder mechanisms  58  can be controlled to limit the amount of torque that is applied to the coupling during actuation.  
         [0026]    Spinning unit  16  serves to rotate a joint of pipe in order to engage or disengage a threaded connection. A preferred spinning unit  16  provides a recess into which a pipe is received for powered rotation by the spinning unit. A preferred spinning unit  16  is also mounted for lateral movement relative to skid  12  so that the location of the interface between a pipe joint and the unit can be controlled and to adjust for movement of the pipe joint as a coupling is engaged or disengaged.  
         [0027]    [0027]FIG. 4 generally illustrates the structure of one embodiment of spinning unit  16 , comprising spinning mechanism  24  and side plates  36  mounted to a frame  22 . Spinning mechanism  24  comprises gear system  42  that is rotated by a motor (not shown) and rotates pipe  40  in either a clockwise or counter-clockwise direction. Gear system  42  is raised and lowered by hydraulic cylinder  44  to maintain the desired contact with pipe  40 . Spinning mechanism  24  also comprises a pair of retaining arms  48  that rotate about pin  50  to maintain roller  52  in contact with pipe  40 . The position of arm  48  is controlled by extending and retracting hydraulic cylinder  46  and preferably can be adjusted so that arms  48  are in a fully open position to allow pipe  40  to be lifted from spinning unit  16 . Spinning unit  16  may be any type of mechanism used to rotate pipe. Spinning unit  16  is preferably able to rotate in both a clockwise and counter-clockwise direction and be hydraulically powered.  
         [0028]    Referring back to FIG. 1, during horizontal boring operations, a site is prepared to receive the drill string as it rises to the surface. Torque wrench and spinner assembly  10  is positioned to align with the drill string as it exits the formation. Assembly  10 , preferably mounted on skid  12 , may be positioned on the surface, truck-mounted, or set into a trench dug into the ground. Assembly  10  may be horizontal or placed at an angle to receive the drill string. Assembly  10  is preferably placed so that pipe coming out of the hole first encounters torque unit  14 . Torque unit  14  and spinning unit  16  may be fully opened so that the drill string can be lowered into the units from above. The drill string may also be inserted axially through torque unit  14  and spinning unit  16 .  
         [0029]    The drill string is positioned, and torque unit  14  adjusted, so that a pipe coupling is properly engaged with the torque unit. Torque unit  14  applies a torque to the coupling to break the connection. Torque unit  14  is then released so that spinning unit  16  can be actuated to rotate the free end of the drill string in order to disengage the coupling. Once the coupling is fully disengaged the pipe joint can be removed. Assembly  10  preferably works in conjunction with a crane, or other lifting apparatus, to safely manipulate the pipe joint after removal from the drill string. This same process can be reversed to add pipe back to the drill string.  
         [0030]    All of the functions of both the torque unit  14  and spinning unit  16  are preferably hydraulically actuated from a control panel that is remote from assembly  10 . Functions may be individually controlled or operate as part of a single hydraulic circuit. The use of hydraulic power also serves to control the amount of torque applied to a coupling so as to ensure consistent, correct connection strengths without risk of damage to the coupling.  
         [0031]    Therefore, the above described assembly allows joints of pipe to be removed from, or added to, a horizontal drill string exiting the ground at the pipe end of a borehole. By providing a remotely operated hydraulic assembly, a single operator can make and break pipe connections safely from a remote location. Furthermore, the use of a hydraulic system allows precise control of the torque applied to a coupling so that damage to the coupling can be limited.  
         [0032]    The embodiments set forth herein are merely illustrative and do not limit the scope of the invention or the details therein. It will be appreciated that many other modifications and improvements to the disclosure herein may be made without departing from the scope of the invention or the inventive concepts herein disclosed. Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, including equivalent structures or materials hereafter thought of, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirements of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.