You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     Embodiments of the present invention generally relate to an apparatus and method for facilitating the connection of tubulars. More particularly, the invention relates to a safety device for preventing well components from colliding. More particularly still, the invention relates to a monitoring system which prevents and/or alerts an operator when a collision between well components is imminent.  
         [0003]     2. Description of the Related Art  
         [0004]     In the construction and completion of oil and gas wells, a drilling rig is constructed on the earth&#39;s surface to facilitate the insertion and removal of tubular strings into a wellbore. The drilling rig includes a platform and power tools such as a hoisting system, an aligning/stabbing tool and a spider to engage, assemble, and lower the tubulars into the wellbore. The hoisting system suspends above the platform from a pulley that is operated by a draw works that can raise or lower the hoisting system in relation to the floor of the rig. The hoisting system includes an elevator, a traveling block, bails, top drive, etc. The aligning/stabbing tool for aligning tubulars comprises a positioning head which is mounted on a telescopic arm which can be hydraulically extended and retracted and pivoted in a horizontal plane to position the tubular. The spider mounts to the platform floor. The elevator and spider both have slips that are capable of engaging and releasing a tubular, and are designed to work in tandem.  
         [0005]     One or more operators perform the construction process on a platform of the drilling rig. The operators monitor the drilling instrumentation, the rig floor and the derrick while assembling tubular strings with the remote control power tools. The distance between an operator and the aligning/stabbing makes it difficult for the operator to judge the location of drilling tools in relation to other drilling tools. The operator&#39;s view of the drilling tools is further obstructed by the drilling tools relative to each other or impaired by adverse weather and poor lighting. These factors sometimes cause an operator to make a mistake thereby causing a collision between the power tools.  
         [0006]     If the hoisting system is raised and lowered with the path of the hoisting system obstructed by a power tool, severe damage to the hoisting system or the power tool can occur. Falling objects from the derrick can cause damage to other equipment, personal injury, or death. Thus, a collision may cause loss of rig time, repair costs, and replacement costs.  
         [0007]     There exists a need for an improved method and apparatus for monitoring the distance between drill rig power tools. Further, there exists a need for a monitoring system that prevents and/or alerts the operator when collisions between drilling tools is imminent.  
       SUMMARY OF THE INVENTION  
       [0008]     Embodiments of the present invention generally relate to methods and apparatus to prevent inadvertent collisions between one drilling tool and another drilling tool during drilling operations. One or more sensors, and/or a controller are used to detect the location of drilling tools. If the drilling tools reach a certain proximity to one another the controller takes action to prevent a collision.  
         [0009]     In one embodiment, the apparatus for preventing well component collisions includes a first component moveable in a substantially vertical plane toward and away from a drill rig floor, a second component moveable toward and away from the well center, and a sensing member for monitoring the location of the first component and a controller.  
         [0010]     In another embodiment, an apparatus for preventing well component collisions comprises a first component moveable along a first predetermined path; a second component moveable along a second predetermined path, wherein the first and second predetermined paths intersect in at least one location; and a sensing member for monitoring the location of the first component relative to the second component.  
         [0011]     In another embodiment, a method for preventing a collision between a first and a second component at a well comprises moving the first component substantially along a first path; moving the second component substantially along a second path, wherein the first and second paths intersect in at least one location; sensing the location of the first component; transmitting the location of the first component to a controller; and preventing the collision between the first component and the second component.  
         [0012]     In another embodiment, an anti-collision system comprises a first sensor for monitoring the location of a first component; a second sensor for monitoring the location of a second component; and a controller for receiving data from the first and the second sensor and controlling functions of the first and second component in order to prevent a collision.  
         [0013]     In another embodiment, an anti-collision system comprises a calculator having a first algorithm for calculating the location of a first component and a second algorithm for calculating the location of a second component. The system also includes a controller communicatively connected with the calculator and at least one of the first and second components in order to prevent a collision.  
         [0014]     In another embodiment, a method for preventing a collision between a first and a second component at a well comprises sensing the location of the first component relative to the second component; transmitting the location to a controller; and utilizing the information transmitted to the controller to move the first component to a predetermined location while avoiding a collision between the components. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of 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.  
         [0016]      FIG. 1  is a schematic view of a drilling rig having an anti-collision system.  
         [0017]      FIG. 2  illustrates a schematic diagram of an anti-collision system.  
         [0018]      FIG. 3  is a flow chart of a typical operation of tubular string or casing assembly with use of the safety system disclosed. 
     
    
     DETAILED DESCRIPTION  
       [0019]     In one embodiment, a monitor system is provided for use with a drilling rig during assembly and disassembly of tubulars in the ground or subsea surface. The system may by utilized to prevent collisions of drilling rig power tools during tubular assembly and disassembly.  
         [0020]      FIG. 1  illustrates a side view of a drilling rig  100  on a surface  170  above a wellbore  180 . The drilling rig  100  includes a draw-works  102  with a cable  150  attached to a pulley system  105 , for raising and lowering a hoisting system  115 . The hoisting system  115  is shown schematically and could include any type of hoisting system, such that disclosed in U.S. Pat. No. 6,742,596 and U.S. Patent Serial Number 2004/0003490 assigned to Weatherford/Lamb, Inc., and herein incorporated by reference in their entirety. The drilling rig  100  further includes a platform  300  with an operator  310  and a control panel  320  to operate one or more tools  350 . The platform  300  and operator  310  are located anywhere on the drilling rig  100 , or offsite if desired. Typically, another operator (not shown) operates the draw-works  102  and the hoisting system  115 , however one operator could do operate both the hoisting system  115  and the tool  350 . In one embodiment there is no operator and the system is completely automated. The draw-works  102  consists of a wheel or spool for winding and unwinding the cable  150 . The cable  150  attaches to a pulley system  105 , at the top of the drill rig  100 , for raising and lowering the hoisting system  115 . If the hoisting system  115  includes a top drive (not shown) a railing system  140  is necessary to prevent rotation of the hoisting system  115 . The center of the drill rig floor  330  includes an opening with a spider  400 . The spider  400  holds a tubular string  210 . A stack of unassembled tubulars  130  is shown on the drilling rig  100 . It should be understood that the unassembled tubulars  130  can be stacked anywhere, and in any configurations so long as the hoisting system  115  is able to lift the tubulars  130 .  
         [0021]     The drilling rig  100  assembles or disassembles tubular strings  210  for use in the wellbore  180 . For exemplary purposes the assembly of a tubular string  210  is described. The spider  400  holds the assembled tubular string  210  so that the top end is above the drill rig floor  330 . The hoisting system  115  grips one of the unassembled tubulars  130  from the stack and positions the tubular over the spider  400 . A tool  350  aligns the tubular  130  with the tubular string  210 . The tool  350  includes a gripping end  353 , for aligning the tubular  130 . An example of an aligning tool can be found in U.S. Pat. No. 6,591,471, assigned to Weatherford/Lamb, Inc., and herein incorporated by reference in its entirety. The tubular  130  connects to the tubular string  210 . With the tubulars  130  and  210  connected the spider  400  disengages the tubular string  210 . With the spider  400  disengaged, the hoisting system  115  supports the tubular string  210  and prevents it from falling into the wellbore  180 . The operator  310  retracts the tool  350  and the other operator lowers the hoisting system  115  until only the end is above the drill rig floor  330 . The spider  400  reengages the tubular string  210 . The hoisting system  115  disengages the tubular string  210  and is brought back to the top of the drilling rig  100 . This process is repeated until the tubular string  210  is complete. Further, the drill rig  100  may include other tools  103  (shown schematically) such as a power tong and or a tailing in and stabbing device. An example of a power tong is disclosed in U.S. Patent Publication Number 2002/0189804 assigned to Weatherford/Lamb, Inc. and herein incorporated by reference in its entirety. Examples of a tailing in and stabbing device are disclosed in U.S. patent application Ser. No. 11/119,958, titled “Tailing In and Stabbing Device,” filed on May 2, 2005, and U.S. Patent Application Publication No. 2004/0131449, which applications are herein incorporated by reference in their entirety.  
         [0022]     The hoisting system  115  is larger than the diameter of the tubular  130 . Therefore, the hoisting system  115  will collide with the tool  350 , if the tool  350  is not retracted to a safe location before the hoisting system  115  passes the tool  350 . In  FIG. 1 , elevation A represents an arbitrary elevation, set by the user, at which the tool  350  may be retracted without damage while the hoisting system  115  is traveling down. Elevation B represents an arbitrary elevation, set by the user, at which a collision is imminent if the hoisting system  115  is not stopped and it is unsafe to retract the tool  350 . One or more sensors  500 ,  502 ,  503 ,  504  and  505  are located on the drilling rig  100  to monitor the location of the hoisting system  115  and the tool  350 . Data collected by these sensors  500 ,  502 ,  503 ,  504  and  505  are relayed to a controller  900 . The controller  900  is adapted to prevent collision between the hoisting system  115  and the tool  350 . Further, the system for preventing collision may be adapted to prevent a collision between any tools on the drill rig  100 , including the power tong and/or the tailing in and stabbing device  103 .  
         [0023]     The controller  900  includes a programmable central processing unit that is operable with a memory, a mass storage device, an input control unit, and an optional display unit. Additionally, the controller  900  includes well-known support circuits such as power supplies, clocks, cache, input/output circuits and the like. The controller  900  is capable of receiving data from the sensors  500 ,  502 ,  503 ,  504  and  505  and other devices and capable of controlling devices connected to it. One of the functions of the controller  900  is to prevent collisions between the hoisting system  115  and the tool  350  as described below.  
         [0024]     A sensor  500  is placed near the cable  150  of the draw-works  102 . The sensor  500  monitors the amount of hoisting cable  150  being let out or pulled in by the draw-works drum  102 . The sensor  500  may comprise a wheel counter in engagement with the cable  150 , a sensor for detecting revolutions of the draw-works  102  drum, a sensor for detecting the revolutions of the drive shaft (not shown) or drive mechanism (not shown) of the draw works drum or any other type of device for measuring the amount of cable  150  extending from the draw works  102  drum. The wheel counter measures the amount of revolutions the wheel in engagement with the cable  150  makes during operation. As shown in  FIG. 2 , the sensor  500  sends data to the controller  900 . The sensor  900  is programmed with information regarding the pulley ratio and start location of the hoisting system  115 . The pulley ratio determines the distance of travel toward the rig floor for a particular cable extension from the draw-works drum  102 . For example, if the pulley ratio is 10 to 1, then for every 10 feet of cable extended from the draw-works drum  102  the hoisting system  115  will travel 1 foot toward the drill rig floor  330 . Thus, the controller  900  is configured to calculate the location of the hoisting system  115  as the cable  150  is wound and unwound from the draw-works drum  102 . The sensor  500  may be used alone or in conjunction with one or more sensors described below in order to prevent a collision on the platform as discussed below.  
         [0025]     A sensor  502  attaches to the tool  350 . The sensor  502  detects the position of the tool  350  and relays the data to the controller  900 . In one embodiment, the sensor  502  is a mechanical sensor attached to the tool  350 , as is known in the art, such as a linear potentiometer, a position transducer, a piston, etc. ( FIG. 2 ). The sensor  502  detects when the tool  350  is extended to an unsafe location and when the tool is in a safe location and relays this data to the controller  900 .  
         [0026]     In another embodiment, the sensor  502  is a position sensor as part of a wireless positioning system. As is known in the art, wireless position sensors use signals, such as radio waves to triangulate the location of the sensor  502 . The sensor  502  is used in conjunction with location tracking components. In one embodiment, three location tags  550 ,  551  and  552  attach to the drilling rig  100  at three separate locations. The location tags  550 ,  551  and  552  can be placed anywhere on the drilling rig  100  although it is preferred to have them spaced apart both horizontally and vertically. The three location tags  550 ,  551  and  552  can then triangulate the location of the sensor  502  thus determining the location of the tool  350  and relay the data to the controller  900 . Further, the sensor  502  can be used in conjunction with previously existing location tracking components, such as the GPS satellites, or Wi-Fi networks.  
         [0027]     Another position sensor  503  attaches to the hoisting system  115  and is incorporated as a part of the wireless positioning system. The location tags  550 ,  551  and  552  locate the sensor  503  as the hoisting system  115  moves up and down and relay this data to the controller  900 .  
         [0028]     In another embodiment, if the hoisting system  115  has a top drive dolly (not shown), a sensor  504  placed on the rail  140  detects when the dolly moves below elevation A and/or elevation B. The sensor  504  can be any type of sensor known in the art, such as a strain gauge, a switch activated by the dolly, etc. The sensor  504  relays this data to the controller  900 .  
         [0029]     In another embodiment, a sensor  505  is placed on the drill rig  100 . The sensor  505  consists of a camera which sends data to the controller  900 . The camera views the location of both the tool  350  and the hoisting system  115 . The controller  900  is equipped with corresponding detection software which determines the location of the hoisting system  115  and/or the tool  350 .  
         [0030]     Regardless of the type of sensor, or if no sensor is used, the controller  900  performs the function of preventing the hoisting system  115  from colliding with the tool  350 . The sensors  500 ,  503 ,  504  or  505  locate the hoisting system  115 , and at least one method of locating the hoisting system  115  is used. In one embodiment, upon the hoisting system  115  reaching elevation A, the controller  900  sends a signal through hydraulic, pneumatic, or electric transmission to the tool  350 . The signal will override the tool controller  320  and retract the tool  350 . Further, the controller  900  can be designed to send a signal directly to a piston  351  which retracts tool  350 . This embodiment does not require the use of a second sensor  502  on the tool  350 , because regardless of the location of the tool  350  the controller  900  will retract the tool  350 . Additionally, if the gripping end  353  is activated and gripping a tubular, the controller  900  can be programmed to not automatically retract the tool  350  until the tubular is safely supported.  
         [0031]     In yet another embodiment, the hoisting system  115  sensor  500 ,  503 ,  504  or  505  operate in conjunction with the sensor  502  on the tool. The sensors  500 ,  503 ,  504  or  505  relay data to the controller  900  indicating the location of the hoisting system  115 . If the sensors  500 ,  503 ,  504  or  505  indicate to the controller  900  that the hoisting system  115  reached the elevation B and sensor  502  indicates to the controller  900  that the tool  350  is in an unsafe position, the controller  900  will override the control to the draw-works drum  102  and stop the hoisting system  115  before a collision occurs. In this embodiment the controller  900  can also raise the hoisting system  115  to a safe location and retract the tool  350 .  
         [0032]     In yet another embodiment, the hoisting system sensors  500 ,  503 ,  504  or  505  operate in conjunction with the sensor  502  on the tool  350 . The sensors  500 ,  503 ,  504  or  505  relay data to the controller  900  indicating the location of the hoisting system  115 . If the sensor  500 ,  503 ,  504 , or  505  indicate to the controller  900  that the hoisting system  115  has reached the elevation A and sensor  502  indicates to the controller  900  that the tool  350  is in an unsafe position, the controller  900  retracts the tool  350 . If the tool  350  fails to retract and the hoisting system  115  reaches elevation B, the controller  900  will stop the hoisting system  115 , as described above.  
         [0033]     In yet another embodiment, the controller  900  prevents the extension of the tool  350  when the hoisting system  115  is in an unsafe position. When the controller  900  detects, through use of sensors  500 ,  503 ,  504 , or  505 , the hoisting system  115  is below elevation A, the controller  900  will override the tool controls  320 . The controller  900  prevents extension of the tool  350  until the hoisting system  115  moves above elevation A.  
         [0034]     The sensors  500 ,  501 ,  502 ,  503   504  and  505  are incorporatable into the drilling rig  100  at any time, making it easy to place the system on a working drilling rig  100 . Further, the anti-collision system can be incorporated to prevent moveable components from colliding with immovable components. To further communicate the unsafe position of the tool  350  to the operator  310 , the sensors  500 ,  501 ,  502 ,  503 ,  504 , and  505  may set off an alarm (not shown), consisting of an audible and/or visual signal.  
         [0035]     In yet another embodiment, rather than using a sensor to determine the position of the hoisting system  115  and/or the tool  350 , the controller  900  may track or calculate the position without a sensor. For example, the position of the components may be determined by keeping track of expected linear movement from a known starting/stopping point as the controller  900  manipulates the hoisting system  115  and/or the tool  350 . Thus, the controller  900  knows the locations of the components at anytime during operation. The controller  900  is programmed so that the components of the drill rig  100  such as the hoisting system  115 , the tool  350  and the other tools  103  will not collide with one another. Further, the anti-collision system may work the same as the embodiments described above but the controller  900  does not need sensors.  
         [0036]      FIG. 3  is a flow chart illustrating a typical operation of a string or casing assembly with the anti-collision system in place. At a first step  600 , the closed spider  400  holds the tubular string  210  and is thereby prevented from moving in a downward direction. At step  610 , the hoisting system  115  engages the tubular  130  from a stack of tubulars. At step  620 , the hoisting system  115  moves the tubular  130  into position above the tubular string  210 . At step  630 , tool  350  extends to engage the tubular  130 , and thereafter, aligns the tubular  130  with the tubular string  210 . At step  640 , the tubular  130  connects to the tubular string  210  by any known method, such as threading or welding the tubulars  130  and  210  together. At step  650 , the operator  310  retracts the tool  350  into a safe position. At step  660 , the spider  400  disengages the tubular string  210 , thus the weight of the string is supported by the hoisting system  115 . At step  670 , the hoisting system  115  lowers the tubular string  210  into the wellbore  180  until only a small portion of the tubular string  210  extends above the spider  400 . At step  680 , the spider  400  reengages the tubular string  210 . At step  690 , the hoisting system  115  disengages the tubular string  210  and raises up to the top of the drilling rig  100 . At step  695 , if the well is complete the method is complete, however if more tubulars  130  need to be assembled the process starts over again at step  600 .  
         [0037]     Step  700  follows step  640  as an alternative method based on the operators  310  action. At step  700 , the spider  400  disengages the tubular string  210 . At step  705 , the operator  310  retracts tool  350  to a safe position. After step  705  the flow charts next step is step  670  described above. The alternative choice after step  700  is step  710 . At step  710 , the operator  310  lowers the hoisting system  115  and the tubular string  210  without retracting the tool  350 . At step  715 , the hoisting system  115  reaches the elevation A as detected by sensor  500 ,  503  or  504  and relayed to controller  900 . One alternative after step  715  is step  720 , the controller  900  automatically retracts the tool  350  as described above. After step  720 , with the tool  350  retracted the next step is back to step  670 , lowering the hoisting system  115 . An alternative route after step  715  is step  725 , the sensor  502  detects the tool  350  is in an unsafe position and relays this data to controller  900 . In the next step  730  the controller  900  retracts the tool  350 . After step  730 , with the tool  350  retracted the next steps back to step  670 , lowering the hoisting system  115 . In yet another alternative after step  715 , in step  735  the hoisting system  115  reaches the elevation B as detected by sensor  500 ,  503  or  504  and relayed to controller  900 . At step  740  the controller  900  stops the hoisting system  115  from moving down. At step  745  the controller  900  or the operator raises the hoisting system  115  to the elevation A. At step  750  the controller  900  or operator retract the tool  350 . After step  750 , with the tool  350  retracted the next step is back to step  670 , lowering the hoisting system  115 . The above-described steps may be utilized in running any drill string in a drilling operation, in running casing to reinforce the wellbore, or for assembling strings to place wellbore components in the wellbore. The steps may also be reversed in order to disassemble the tubular string.  
         [0038]     While the foregoing is directed to embodiments 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.

Summary:
Methods and apparatus are provided to prevent collisions between one drilling tool and another drilling tool during drilling operations. If the drilling tools reach a certain proximity to one another, a controller takes action to prevent a collision.