Patent Application
20210087895
The present invention generally involves an interlock for a drill rig and a method for operating the drill rig. Particular embodiments of the present invention may be incorporated into land-based or offshore drill rigs used for oil/gas production and/or well service operation to reduce or prevent personnel injury or equipment damage when changing the length of a drill string.
Drill rigs are commonly used in oil and gas production and well service operations to bore substantial distances below the earth's surface. A drill rig generally includes a drawworks for raising and lowering a drill string in a borehole. The drawworks generally includes a large drum or spool that holds a cable. The cable extends from the drum to a derrick that supports a block and tackle arrangement holding a traveling block. The traveling block provides a mechanical advantage for raising and lowering the drill string in the borehole. A clutch releasably connects a drive system to the drum to rotate the drum to reel in the cable. To lower the drill string, the clutch may disengage the drive train from the drum, and a brake connected to the drum may be released to allow the weight of the drill string to rotate the drum to release the cable from the drum.
The drill string refers to segments of pipe serially connected to extend into the borehole. The drill string may include hundreds of segments connected by threaded connections at the ends of the segments. Each segment may be approximately thirty feet in length and weigh several hundred pounds. The addition and removal of segments typically involve the coordinated efforts of multiple operators on the drill rig using tools such as tongs (large, self-locking wrenches). When adding a new segment to a drill string, a first tong (a “makeup tong”) is used to spin the new segment so that the new segment threads into the end segment of the drill string (i.e., “makeup” a new segment) to make the drill string longer. When removing a segment from a drill string, a second tong (a “breakout tong”) is used to spin the end segment to unthread and remove (i.e., “breakout”) the end segment from the drill string to make the drill string shorter.
To rotate a segment, a floor worker may move a tong from its storage area and connect the tong to a segment to be added/removed. The tong may be further connected to a mechanical cathead that pulls on the tong to generate the torque required to tighten/loosen the segment to be added/removed. The floor worker may move another tong from its storage area and connect the other tong to the drill string to hold the drill string and keep the drill string from rotating while the segment to be added/removed is rotated. While the tongs are not being used, they are generally stowed out of the way in a storage area on the drill rig floor.
The repetitive nature of adding and removing segments from the drill string, noise associated with the operations, the weight of the segments and equipment manipulating the segments, the magnitude of the forces generated, and various other personnel and environmental factors create an inherently dangerous operating environment. For example, hundreds of segments will be required for a borehole that is 8000 feet deep, requiring floor workers to repeat the above process hundreds of times, some of which will occur late in a work shift and during early morning hours when workers may not be particularly alert and attentive.
A problem arises should the drawworks be activated while a tong is connected to a segment or the drill string which may seriously damage the tong, cathead, and other equipment as well as injure operators. Such may result in interruptions to the drilling operations, expensive repairs, training, personnel injury, and lost revenue. Therefore, the need exists for an improved drill rig system and method for operating the drill rig that incorporates one or more interlocks to protect the tongs while providing a safer and more reliable drill rig operation process.
Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.
One embodiment of the present invention is an interlock between a drawworks and a tong that includes a means for sensing a position of the tong. An interlock signal is generated by the means for sensing the position of the tong and is reflective of the position of the tong. A lock operably connected to the drawworks receives the interlock signal and disables operation of the drawworks if the interlock signal meets a predetermined criterion.
An alternate embodiment of the present invention is an interlock for a drill rig that includes a drawworks having a drum operably connected to a drive system and a brake. A cable extends from the drum of the drawworks to a block and tackle arrangement holding a traveling block, and operation of the drawworks causes the drum to release or retract the cable. The interlock further includes a tong and a means for sensing a position of the tong. An interlock signal is generated by the means for sensing the position of the tong and is reflective of the position of the tong. A lock operably connected to the drawworks receives the interlock signal and disables operation of the drawworks if the interlock signal meets a predetermined criterion.
In yet another embodiment of the present invention, a method for operating a drill rig includes operating a drawworks to raise and lower a drill string and operating a tong to add/remove segments to the drill string. The method further includes sensing a position of the tong, generating an interlock signal that reflects the position of the tong, and disabling the drawworks if the interlock signal meets a predetermined criterion.
Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.
A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
As used in the claims, the definite article “said” identifies required elements that define the scope of embodiments of the claimed invention, whereas the definite article “the” merely identifies environmental elements that provide context for embodiments of the claimed invention that are not intended to be a limitation of any claim.
Embodiments of the present invention include a drill rig and method for operating the drill rig that incorporates one or more interlocks to ensure safe and reliable operation of the drill rig. Referring now to the drawings,
Referring now more particularly to
In the particular embodiment shown in
In yet another particular embodiment, the means for sensing the position of the tong 38 may be the extendable tether 44 connected to the tong 38 and reel 50 as depicted in
As shown in
As shown in
The predetermined criterion may be selected to prevent operation of the drawworks 12 when a tong 38 is in any position that would allow the tong 38 to be connected to the segment 36 or drill string 16. For example, the tong 38 cannot be connected to the segment 36 when the tong 38 is positioned within its storage area 40. As a result, the predetermined criterion may be any interlock signal 66 that indicates the tong 38 is in any position other than in the storage area 40. Referring to the embodiments shown in
As shown in
At block 78, the tongs 38 are operated to add/remove the segment 36 from the drill string 16. At block 80, the tongs 38 may be returned to the storage area 40. As the sensors 58, 60 detect that the tongs are in the storage area 40, the interlock signal 66 changes, and the lock 68 enables operation of the drawworks 12, allowing a floor operator to use the drawworks 12 to raise/lower the drill string 16 as needed. The method then repeats for the next segment 36. The interlock 54 and method for operating the drill rig 10 thus provide enhanced safety and protection for both equipment and personnel by preventing inadvertent operation of the drawworks 12 while any tong 38 is engaged with the segment 36 or drill string 16.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
