Patent Publication Number: US-2012043071-A1

Title: Interlock system for tubular running tools

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     THIS APPLICATION CLAIMS THE BENEFIT OF U.S. PROVISIONAL PATENT APPLICATION SER. NO. 61/373,633, FILED AUG. 13, 2010, WHICH IS INCORPORATED HEREIN BY REFERENCE FOR ALL PURPOSES. 
    
    
     FEDERALLY SPONSORED RESEARCH 
     Not Applicable 
     BACKGROUND OF INVENTION 
     1. Field of Invention 
     The present invention pertains to an interlock system for use with tubular running systems. More particularly, the present invention pertains to an interlock system for use with casing running tools including, without limitation, casing running tools utilized with rig top drive systems. 
     2. Description of Related Art 
     Once a well bore has been drilled to a desired depth, large diameter pipe called casing is frequently installed in said well bore and cemented in place. Such casing is usually inserted into a well in a number of separate sections of substantially equal length called “joints.” The joints are typically screwed together or otherwise joined end-to-end at the surface in axial alignment in order to form a substantially continuous “string” of pipe that reaches downward. As the bottom or distal end of the pipe string penetrates further into the earth, additional sections of pipe are added to the upper end of the pipe string at the surface. The process is repeated until a desired length of casing is installed into a well. 
     Conventional casing installation operations typically involve specialized crews and equipment that must be mobilized to a rig site for the sole purpose of running casing into a well. During conventional casing operations, powered casing tongs, casing elevators and spiders, and at least one dedicated hydraulic power unit must typically be mobilized to a well location and set up immediately prior to the casing installation operation. Moreover, specialized casing crews typically must rig up and operate the equipment, connect the joints of casing that are installed in the well, and then demobilize the equipment following completion of the operation. 
     Interlock systems have been developed for use during conventional casing installation operations. Such interlock systems typically assure that one set of slips is gripping a casing string at all times during the installation process, such that one set of slips (the spider slips, for example) may not be released from the casing until the other set of slips (the elevator slips, for example) has a firm grip on the casing string. Such prior art interlock systems typically act to prevent the elevator slips and/or the spider slips from inadvertent actuation unless the other set of slips are fully set in gripping engagement against the casing string. 
     Such existing interlock systems are especially beneficial for conventional elevator and spider configurations in order to reduce the likelihood of inadvertent dropping of a casing string (from either the elevator or the spider) due to human error associated with the operation of such tools. Existing interlock systems generally require spider and elevator slips to communicate with a remote panel. A logic system associated with such panel generally controls the opening of the elevator and spider slips, rather than the operator. 
     Many modern drilling rigs are equipped with top drive drilling systems. Such top drive systems, which can be used to pick up sections of pipe, connect pipe sections together, and provide the torque necessary to drill wells, are now commonly being used in connection with the installation/running of casing strings. Specifically, a method of running casing using a rig&#39;s top drive system together with a specialized casing running tool (“RT”) has become increasingly popular in recent years. In essence, the top drive and RT are taking the place of the elevators, tongs, and casing fill-up tools used during conventional casing installation operations. 
     In many cases, casing can be run more efficiently and for less cost using an RT than with conventional casing crews and equipment. RT&#39;s can be used to pick up and stab joints of casing, often eliminating the necessity for personnel to be located at an elevated location on a rig, such as in the derrick on the casing stabbing board. Because a rig&#39;s top drive equipment can provide torque to make up threaded casing connections, specialized casing tongs are frequently not required. Further, the RT permits periodic rotation and/or reciprocation of casing within a well, which can often improve the efficiency and overall quality of the casing installation operation. 
     In most cases, a specialized RT is connected immediately below a rig&#39;s top drive unit prior to commencement of casing installation operations. A single-joint elevator, frequently supported by a RT, is typically used to lift individual joints of casing from a V-door or pipe rack into a derrick above a well. The lifted “upper” joint of casing is then vertically aligned with and stabbed into the uppermost portion of a casing string that was previously partially installed in said well. The top drive and attached RT are then lowered until the RT engages the top of the new “upper” joint being added. The slips of the RT are then engaged to grip the “upper” joint of casing, and the top drive is actuated to apply the required torque (through the RT) to make up the threads being connected. Once the threaded connection is completed, the spider slips can be released, and the casing string can be lowered into the well using the top drive/RT. 
     During conventional casing installation operations, either the spider. slips or the elevator slips are gripping the casing string, but typically not both. However, RT casing installation operations include an additional step in the process—a time when the RT is rotating the “upper” joint of pipe to connect said joint with the casing string situated below that is suspended within the well by the spider slips. During this step, both the RT slips and the spider slips are in a closed position and are gripping the pipe. This additional step in the casing running operations creates a problem for conventional interlock systems. 
     With conventional interlock systems, having both the elevator (or RT) slips and spider slips in a closed position (such as during the above described make-up step) will satisfy the logic requirements of such interlock devices, thereby permitting one or the other to be opened by an operator. However, the spider slips must not be opened during this step because such slips are supporting the casing string in the wellbore. Similarly, the RT slips should not be opened during this step, because such slips are supporting the “upper” joint that is being made up. This presents a potentially unsafe situation, and renders conventional interlock systems unsuitable for most casing installation operations utilizing an RT. 
     Thus, there is a need for a versatile interlock system that can be safely and effectively used during casing installation operations including, without limitation, those performed using casing RT systems. In addition to other beneficial functions, the interlock system should prevent (that is, lock out) the inadvertent opening of lower (spider) slips or upper (RT) slips during casing installation operations including, without limitation, during periods when a section of pipe is being held by RT slips while such pipe is being made up to a casing string below that is being gripped and supported by spider slips. 
     SUMMARY OF THE INVENTION 
     The present invention comprises an interlock system for use with tubular installation systems including, without limitation, casing running tools that are utilized in connection with rig top drive systems. Among other functions, the method and apparatus of the present invention can be utilized to provide confirmation from: 
     a RT to a spider to allow spider slips to open; 
     a spider to a RT to allow RT slips to open; 
     a weight indicator to top drive; 
     a weight indicator to a RT 
     a torque turn monitor 
     a load cell to spider 
     Existing prior art interlock systems can be used to provide communication between a RT and spider; however, as described in detail above, during certain steps in the casing installation process using an RT such existing interlock systems can permit an unplanned, unsafe event. The present invention utilizes a “third leg” of logic that permits spider slips to be controlled by variables including, without limitation, casing string weight—if there is not sufficient string weight, such slips will be “locked out” and will not be permitted to open. 
     In many instances, a RT will have an isolated lock that is not integrated or otherwise in communication with a spider. Utilizing a signal to unlock the RT, a spider may be added to the unlock circuit such as, for example, using a cam operated hydraulic valve. By re-routing the unlock signal through the spider, such as using a cam operated hydraulic valve, the unlock signal is not sent to the RT until the spider is set. This function is no longer controlled by an operator, but by the spider position itself. 
     The master lockout sequence of the present invention is crucial for an interlock system to function with an RT. Existing prior art interlock systems were designed to recognize when both upper (elevator) and lower (spider) slips are closed and gripping pipe so that one or the other can be opened. However, when RT systems are used to install casing, there are times when both the upper (RT) and lower (spider) slips are engaged and carrying a load, yet neither can be safely opened at this time. By measuring tension on the RT and/or a compressive load on the spider, it is possible to determine when the RT has applied sufficient torque to connect a single joint to the casing string and lift said string. At this time only can the spider slips be opened to lower the pipe string in the well bore. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, the drawings show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed. Further, dimensions, materials and part names are provided for illustration purposes only and not limitation. 
         FIGS. 1 through 9  depict schematic illustrations of an RT slip assembly and spider slip assembly, together with interlock functionality, fluid pressure connections, operator actuated valves and position actuated valves of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     While the present invention is described herein with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to the present invention without departing from the scope of such invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the present invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments (and legal equivalents thereof) falling within the scope of this disclosure. 
     It is also to be observed that the present invention is described herein as employing pneumatic and hydraulic actuated valves and other components. It is to be observed that the communication and control circuitry of many of said elements of the present invention can be varied or, in some cases, replaced by other actuation means such as electronic circuitry or radio telemetry. 
     The present invention comprises an interlock system for use with tubular installation systems including, without limitation, casing running tools utilized with rig top drive systems. Among other functions, the method and apparatus of the present invention can: 
     Provide conformation information from a RT to a spider to allow spider slips to open; 
     Provide conformation information from a spider to a RT to allow RT slips to open; and 
     Utilize conformation information from:
         1. weight indicator from top drive   2. weight indicator from RT   3. torque-turn monitor   4. load cell from spider       

     Prior art interlock systems can be used to provide communication between a RT and a spider assembly; however, during certain periods before pipe make-up using a RT, such existing prior art interlock systems can permit an unplanned, unsafe event. Utilizing a third leg of logic, the present invention permits a spider assembly, including the slips thereof, to be controlled by string weight. If a predetermined sufficient weight is not recognized, neither RT slips nor spider slips will be allowed to open. 
     Description of Numbered Elements: 
     1 3 position, 4 way detent valve—hydraulic (control cabinet) 
     2 3 position, 4 way detent valve—hydraulic (control cabinet) 
     3 3 position, 4 way pilot operated valve—hydraulic (control cabinet) 
     4 2 position 3, way palm operated valve—pneumatic (control cabinet) 
     5 2 position 4 way pneumatic valve with hydraulic pilot with pneumatic spring (spider lockbox) 
     6 2 position 4 way pneumatic valve with pneumatic pilot and spring return (spider lockbox) 
       7  filter regulator lubricator (spider lockbox) 
     8 regulator for pneumatic spring (spider lockbox) 
     9 2 position, 4 way pneumatic valve with pneumatic pilot and spring return (spider) 
     10 2 position, 4 way pneumatic valve with treadle actuator (spider) 
     11 2 position, 3 way hydraulic cam operated valve (spider) 
     12 pilot operated pneumatic check valve (spider) 
     13 actuator (spider) 
     14 RT actuator (RT) 
     15 pilot operated hydraulic check (RT) 
     16 hydraulic accumulator (RT) 
     17 solenoid actuated 4 way air valve 
     18 pneumatically piloted 2 position hydraulic valve, 
     19 programmable logic controller/processor 
     20 tension load cell for measuring tension on top drive 
     21 compression load cell for measuring load on the spider 
     The present invention comprises an interlock system utilizing an integral lock on a casing RT and its functionality with an appropriate spider, through the use of an intermediate lockbox. 
     A RT has an integral lock that is not in communication with or integrated with a spider. Utilizing an unlock system from the RT, a spider may be added to the unlock circuit via a cam operated hydraulic valve. By re-routing the RT unlock signal through the spider cam operated hydraulic valve, the RT unlock signal is not sent to the RT until the spider slips are set. This function of the control panel is no longer controlled by an operator, but by the spider slip position. 
     Adding a lock box to interpret signals of the casing running tool in its set position, a hydraulic signal is sent to the lock box and activates valve in a spider lock box which, in turn, routes air from a filter regulator lubricator to the inlet port of another valve in the spider lock box. When the spider slips are ready to be opened, the RT operator can depress the palm button valve (or other similar actuation device) located on the RT control cabinet. This in turn sends a pilot signal to actuate a valve at the spider, putting air at the inlet of a treadle valve. At this point the spider operator can open spider and allow the casing string to be lowered into the well. 
     Referring to the drawings, the following describes a representative operational sequence of the present invention: 
     FIG.  1 —RT Slips Initial Closing, and Spider Slips Closed 
     In this step in the sequence of closing the RT valve ( 1 ), said valve is shifted into the slip set position directing pilot pressure to valve ( 3 ) at the same time valve ( 2 ) is in its home position and not yet shifted. This also directs pilot pressure to the opposite pilot on valve ( 3 ), which causes valve ( 3 ) to shift to the center position. Pressure is blocked in this position. In this stage, no signals are sent to the spider lockbox and the spider slips are closed, and locked in the set position. 
     FIG.  2 —RT Slips Set, Spider Slips Closed, RT Set Signal Sent to Lockbox 
     In this step in the sequence, the RT is set and locked when valve ( 2 ) is shifted into its lock position. This removes pressure from pilot at valve ( 3 ) causing this valve to shift and allow set pressure to be applied to the RT actuator. This sets the RT slips on the pipe and locks into place. At the same time pressure at valve ( 2 ) is sent to the hydraulic pilot on valve ( 5 ), this shifts the valve and sends pneumatic pressure to valve ( 6 ). At this point the spider slips have still not been actuated, as the spider lockbox is waiting for signal from a RT operator. 
     FIG.  3 —RT Slips Set, Spider Slips to Open 
     Now that set signal has been received at the spider lockbox, a RT operator can now physically operate palm button valve ( 4 ) on the control cabinet. This shifts valve ( 6 ) in the spider lock box and sends a pilot signal to valve ( 9 ) on the spider. Now air is present at treadle operated air valve and the spider operator shifts treadle valve and opens the spider slips. 
     FIG.  4 —RT Slips Set, Spider Slips Open 
     With the RT slips set and the spider slips open in this step, palm button operated valve ( 4 ) has been released and the spider is now “dead” without power and is locked into place with mechanical lock located on said spider. Cam operated valve ( 11 ) is shifted over with spring and the flow path for the RT unlock signal is connected to tank, not allowing RT to be opened by operator. 
     FIG.  5 —RT Slips Set, Spider Slips Closing 
     In this step in the sequence, the RT slips are still in set/locked position, energizing valve ( 5 ) which supplies pressure to valve ( 6 ). The RT operator can depress the palm button valve ( 4 ) that sends a pilot signal to shift valve ( 6 ) in the spider lockbox which sends a signal to shift valve ( 9 ) on the spider and sends air to treadle valve ( 10 ) on the spider. The spider operator can then shift said treadle valve to close spider. 
     FIG.  6 —RT Slips Released, Spider Slips Closed 
     In this step in the sequence, spider slips are is closed and valve ( 1 ) has been shifted to initiate unlocking of the RT actuator. When valve ( 1 ) is shifted it sends a signal to cam operated valve ( 11 ) that has been depressed when the slips closed. This routes the unlock signal back to the cabinet, and eventually to the pilot operated check ( 15 ) which unlocks the RT and can now be released. 
     FIG.  7 —RT Slips Unlocked and Released, Spider Slips Closed 
     In this step in the sequence, valve ( 2 ) is shifted and pressure is applied to valve ( 3 ) and shifts power to the release side of the RT actuator. With both the unlock signal and the release signal sent to the RT, the RT slips are released and the RT can be disengaged or removed from the pipe. 
     FIG.  8 —RT Slips Set, Spider Slips Closed (Tension or Load is Not Sufficient to Unlock Circuit Through PLC/Processor) 
       FIG. 8  depicts a master lockout step in the sequence. At any time during any of the afore-described steps in the sequence wherein the spider slips and RT slips are engaged and gripping pipe, yet there is not sufficient predetermined load measured by compression load cell ( 21 ) or tension load cell ( 20 ) being registered by the PLC/processor ( 19 ), said PLC/processor will send a signal that will activate a solenoid on valve ( 17 ). Said valve ( 17 ) diverts pressure that would normally be on the inlet of palm operated valve ( 4 ) to air pilot operated valve ( 18 ). This effectively blocks or eliminates the signal required by the spider to allow pressure to be sent to treadle valve ( 10 ), thereby making the spider slips unable to open. 
     By diverting this pressure to valve ( 18 ), the valve is caused to shift to the closed position, blocking any unlock signal from valve ( 1 ) from reaching cam operated valve, blocking this signal from reaching cam operated valve  11 . As such, a signal to unlock or release the RT cannot be sent, thus making the RT slips unable to open. Until the system (and, more specifically, programmable logic controller/processor  19 ) has sensed the predetermined acceptable tension or compressive load either at the RT or the spider, then the status will remain unchanged and the condition will stand. For example, the slips of the RT cannot release until and unless a sufficient, predetermined weight load at the spider slips is recognized. However, once the programmable logic controller/processor  19  has sensed the predetermined acceptable tension or compressive load either at the RT or the spider, solenoid valve ( 17 ) will release and normal operational conditions can resume. 
       FIG. 9  depicts a variation of the schematic illustrations of the RT assembly and spider assembly, together with interlock functionality, fluid pressure connections, operator actuated valves and position actuated valves of the present invention depicted in  FIG. 8 . 
     A torque turn monitor can also be included in the system to ensure that the threaded connection between the sections of pipe held by the RT and spider assembly is fully engaged, and that said threaded connection is sufficiently strong to support the weight of the entire pipe string below. In the preferred embodiment, when said component is included, a signal is sent from said torque turn monitor to programmable logic controller/processor  19  when said monitor detects that a threaded connection is satisfactorily made to predetermined acceptable standards. Until this occurs, the pressure circuit of the present invention will not permit the spider slips of the present invention to open and release the pipe. 
     This master lockout sequence of the present invention is crucial for an effective casing RT interlock. Conventional interlock systems are designed to prevent either spider slips or elevator slips from opening at the same time when both are holding pipe. However, when a RT serves as an elevator and a tool to provided torque to pipe during the make-up or connection process, both the RT slips and spider slips will carry a load at the same time. However, neither can be opened at this time. By measuring tension on the RT and/or a compressive load on the spider, it is possible to determine when the RT has applied sufficient torque to connect a single joint to the string—that is, when the RT lifts the string. It is only at this stage that the present invention will “unlock” the system, so that the spider slips can be opened and the pipe string lowered into the well. 
     The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention. The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention.