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CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims priority to U.S. Provisional Patent Application No. 60/700,624, filed on Jul. 19, 2005 and titled “Single Joint Drilling System,” which is hereby incorporated by reference herein. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable. 
   BACKGROUND 
   The present invention relates generally to methods and apparatus for drilling wells. More specifically, the present invention relates to systems for drilling wells utilizing single joints of pipe. 
   Many smaller drilling rigs store tubular members, such as drill pipe, drill collars, and casing, in horizontal storage areas outside of the rig. As the different tubular members are needed, they are brought to the drill floor one at a time and added to the string. Handling these tubular members has historically been a highly manual job using winches or other lifting appliances within the rig. Automated systems for use in these “single joint” rigs must be able to safely handle a variety of tubular members while not slowing down drilling or tripping processes. 
   One important step in the pipe handling process is manipulating pipe and other tubular members in the horizontal storage areas before they are moved to the drilling rig. In many operations, horizontal pipes aye manipulated using forklifts or other manually-operated lifting devices. These manual systems limit the efficiency of the overall system and also often place workers in areas where heavy loads are being moved, thus creating safety concerns. Thus, there remains a need to develop methods and apparatus for pipe handling and drilling systems, which overcome some of the foregoing difficulties while providing more advantageous overall results. 
   SUMMARY OF THE PREFERRED EMBODIMENTS 
   Embodiments of the present invention include a pipe handling system comprising a pipe rack moveably coupled to a stationary frame. The pipe rack is configured to support a plurality of pipes between a loading end and a storage end. The pipe rack is moveable between a loading position where the loading end is positioned at a higher elevation than the storage end and an unloading position wherein the storage end is positioned at a higher elevation than the loading end. An arm is rotatably coupled to the loading end of the rack and is configured to engage a single pipe and move the single pipe onto or off of the pipe rack. 
   Thus, the embodiments of present invention comprise a combination of features and advantages that enable substantial enhancement of moving pipe and other tubular members to and from a drilling rig. 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 
     For a more detailed description of the preferred embodiment of the present invention, reference will now be made to the accompanying drawings, wherein: 
       FIGS. 1A-F  illustrate the loading of pipe from a pipe handling system constructed in accordance with embodiments of the invention; 
       FIGS. 2A-F  illustrate the loading of pipe onto the pipe handling system of  FIGS. 2A-F . 
       FIGS. 3A-H  illustrate the loading of pipe from a pipe handling system constructed in accordance with embodiments of the invention; and 
       FIGS. 4A-H  illustrate the loading of pipe onto the pipe handling system of  FIGS. 3A-H . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to  FIG. 1A , pipe handling system  100  comprises rack  102 , frame  104 , tilting mechanism  106 , elevated stop  108 , and pipe unloading assembly  110 . Unloading assembly  110  comprises lifting block  114  and rotating arm  116 . Rack  102  is moveably coupled to frame  104  at pivot  118 . A plurality of pipes  120  are stored on rack  102  between storage end  122  and loading end  124 . Tilting mechanism  106  is coupled to frame  104  and rack  102  so as to control the height of storage end  122  of rack  102  relative to loading end  124 . By varying the height of storage end  122 , gravity can be used to move the pipes  102  along rack  102 . In certain embodiments, frame  104  may be coupled to erector system  400  so that pipe handling system  100  is transported with and operates as an integrated component of the erector system. 
   In  FIG. 1A , rack  102  is in a loading position where storage end  122  is higher than loading end  124 . Gravity will move pipes  112  along rack  102  toward loading end  124  until the pipes contact elevated stop  108 . Referring now to  FIG. 1B , to load a single joint of pipe  112  onto erector system  400 , lifting block  114  is raised, pushing a single joint of pipe  112  upward. The pipe  112  moves over and past elevated stop  108  toward the end of rack  102 . Lifting block  114  is then lowered so that the remainder of pipes  120  can move downward until contacting elevated stop  108 . 
   At the end of rack  102 , pipe  112  is stopped by arm  116 , which is disposed in a raised position. Arm  116  is coupled to gear  130  on which is mounted chain  132 . Chain  132  is coupled to each end of double-acting linear actuator  134 , which is coupled to rack  102 . As rod  136  of linear actuator  134  is extended and rod  138  is retracted, gear  130  and arm  116  rotate. The rotation of arm  116  continues until pipe  112  is lowered onto erector system  400  as is shown in  FIG. 1D . Arm  116  continues rotating downward so that is out of the way of erector system  400  as shown in  FIG. 1E . Erector system  400  can then lift pipe  112  upward and away from pipe handling system  100 . 
     FIGS. 2A-F  illustrate pipe handling system  100  being used to store pipes being removed from a drill string. When moving pipes  112  from erector system  400 , tilting mechanism  106  lowers the storage end  122  of rack  102  so as to angle the rack away from erector system  400 . Lifting block  114  and elevated stop  108  are retracted into rack  102  so as to provide a smooth surface along which pipe  112  can roll. Once pipe  112  is lowered and released by erector system  400 , arm  116  rotates upward so as to lift the pipe from the erector. Arm  116  continues to rotate until pipe  112  falls onto rack  102  where it will roll toward the far end of the rack. 
   Another pipe handling system is shown in  FIGS. 3A-H  and  4 A-H. Pipe handling system  200  comprises frame  202  that is pivotally mounted on base  204 . The incline of frame  202  is controlled by piston  206  to that the relative heights of storage end  221  and loading end  222  of frame  202  can be adjusted. The loading and unloading of pipe into handling system  200  is done by pipe moving assembly  210 . Pipe moving assembly  210  comprises extendable finger  214 , rotatable arm  216 , drive motor  218 , and rotary motor  224 . Assembly  210  is slidably mounted to a vertical member of frame  202  so that drive motor  218  engages gear rack  220 . 
   The unloading of pipe from handling system  200  is illustrated in  FIGS. 3A-H . Piston  206  inclines frame  202  so that the frame is in a loading position where pipe joints  212  tend to move toward pipe moving assembly  210 . Finger  214  extends to separate a single joint of pipe from the row of pipes stored in frame  202 . Assembly  210  the moves upward until pipe  212  clears frame  202 , as shown in  FIG. 3B . Pipe  212  will roll down assembly  210  until it contacts arm  216 , which is in an elevated position. With pipe  212  resting against arm  216 , assembly  210  moves downward along frame  202  to the position shown in  FIG. 3D . Motor  224  then rotates arm  216  so as to lower pipe  212  into erector system  400  and continues rotating until reaching a lowered position as shown in  FIG. 3E . With arm  216  in a lowered position, erector system  400  can capture pipe  212  and move the pipe to the drill floor. Once erector system  400  has moved out of the way, assembly  210  is moved back to uppermost row of pipes and arm  216  is rotated back to the elevated position. 
   The loading of pipe from erector system  400  back into handling system  200  is illustrated in  FIGS. 4A-H . Piston  206  inclines frame  202  so that pipe joints  212  tend to move away from moving assembly  210 . Mover assembly  210  is disposed adjacent to erector system  400 , once erector system  400  lowers pipe  212  to a horizontal position. Once erector system  400  disengages pipe  212 , arm  216  rotates to lift pipe  212  from erector system  400 . Mover assembly  210  then moves up frame  202  until pipe  212  clears the top of the frame. Once inside frame  202 , pipe  212  is restrained by extended finger  214  and bumper  215 . Mover assembly  210  moves back down frame  202  until pipe  212  is at the row of pipe being loaded. Finger  214  then retracts and pipe  212  will roll into position within frame  202 . Mover assembly  210  is then moved back to the proper elevation to receive pipe from erector system  400  and arm  216  is rotated back to its lowered position. 
   Horizontal pipe handling systems can be used with a variety of pipe erectors and other pipe handling systems. For example, a horizontal pipe handling system may be utilized to move pipes onto and off of a pipe erector that moves the pipe from the horizontal storage position to a drill floor. Horizontal pipe handling systems can also be used with conventional pipe hoisting systems as well as other handling systems. Horizontal pipe handling systems may operate as separate components within a drilling system or be combined into an integrated system with a pipe erector or hoisting system. It is also understood that horizontal pipe handling systems can be used with a variety of oilfield tubulars, including drill pipe, drill collars, casing, and tubing. 
   While preferred embodiments of this invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teaching of this invention. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the system and apparatus are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims.

Summary:
A pipe handling system comprises a pipe rack moveably coupled to a stationary frame. The pipe rack is configured to support a plurality of pipes between a loading end and a storage end. The pipe rack is moveable between a loading position where the loading end is positioned at a higher elevation than the storage end and an unloading position wherein the storage end is positioned at a higher elevation than the loading end. An arm is rotatably coupled to the loading end of the rack and is configured to engage a single pipe and move the single pipe onto or off of the pipe rack.