Patent Application
20140265389
The present invention relates generally to an apparatus and system for handling blowout preventer (“BOP”) stacks. More specifically, the present invention relates to a BOP lifting and handling device for securing and lifting a complete BOP stack during transport as well as handling at a wellhead.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the exploration of oil, gas and geothermal energy, drilling operations are used to create boreholes, or wells, in the earth. Drill rigs are typically used for such operations, and drill rigs used in subterranean exploration must be transported to the locations where drilling activity is to be commenced. Adding to the complexity, drill rigs are typically large, complex pieces of machinery that generally must be disassembled for transport and then reassembled at the destination. In a majority of these transport scenarios, the drill rigs are moved by truck and trailer.
The process for assembling the multitude of parts and components of a drill rig for drilling operations is typically known in the industry as “rig up.” During rig up, crews may utilize cranes, rig up trucks, forklifts, and other specialized equipment for moving the parts of the drill rig into place. The process may be very time consuming, and may take several days to complete, depending on the type of rig being assembled and problems encountered during the process. During the rig up process, no drilling work is able to be performed. This adds to the overall cost of the drilling process in terms of crew and equipment expenses. As the drilling process cannot begin until the drill rig has been fully assembled, it is generally desirable to complete the rig up process as quickly and efficiently as possible, thereby minimizing this downtime. However, rig up is a particularly dangerous component of the drilling process, and the speed of the rig up may not be increased at the sacrifice of safety to the drilling crew.
Once drilling work has been completed at a particular well, the rig up process is performed in reverse order (“rig down”) to substantially disassemble the drill rig for transport and rig up at a different location. As expected, the rig down process may require roughly the same amount of time as the rig up process and further adds to downtime and costs for operating a drill rig. While it is imperative that such downtime also be minimized, it cannot be done at the sacrifice of the safety of the drilling crew.
A particularly time consuming and labor intensive task during the rig up and rig down process is the transport and handling of the blowout preventer (“BOP”) stack. As known in the oil field services industry, a BOP is a large, specialized valve installed in redundant, serial stacks that is used to seal, control and otherwise monitor the flow of liquids and gases out of oil and gas wells. Due to the extreme pressures produced by subterranean hydrocarbons, BOP stacks may have a 13″ or greater bore diameter and be rated for working pressure up to and exceeding 10,000 psi. The BOP stack is installed at the wellhead beneath the drill floor so as to control the flow of fluids entering and exiting the well. Additionally, downhole equipment must pass through the BOP stack to be placed downhole. Because the BOP stack is the last line of defense in preventing a blowout, it is critical to the overall safety of the drill rig.
As understood from the above discussion, several individual BOPs are usually stacked on top of one another to form a “BOP stack.” Such stacks may be several meters tall and weigh tens of thousands of pounds. Thus, BOP stacks pose a significant challenge during transportation and positioning during the rig up and rig down process. BOP stacks are at least partially disassembled for transport on trucks, as there is no practical way to transport a fully assembled BOP stack. This disassembly and subsequent reassembly process requires a significant amount of time that adds to the overall time required for rig up and rig down.
Once the BOP stack is assembled, it must be positioned under the rig floor directly over the wellhead. This procedure is also difficult and time consuming because the large BOP stack must be precision located underneath a previously erected drill rig and centered on the axis of the well. Such careful placement requires fine adjustment in at least two horizontal directions. The BOP stack may also need adjustment in the vertical direction due to potential elevation differences at the wellhead. Finally, the BOP stack must be rotated into alignment at the wellhead with one of several connectors which secure the BOP stack to the wellhead.
Most BOP handling systems and methods currently being used involve transferring the BOP stack from one piece of equipment to another, such as from a skid to an overhead lifting system. Many of these overhead lifting systems, such as cranes or trolleys, involve lifting and suspending the BOP, which consumes significant amounts of time and resources to perform safely. When the BOP is lifted in such a manner, it is unwieldy and difficult to maneuver due to the precarious nature of suspending such a heavy load. The lifting of a BOP presents particular safety concerns to the crew working around it, as a mishap and slip of the BOP from the lifting assembly may severely injure crew members.
Prior art provides a two piece lifting assembly that is assembled around the stack. It requires alignment of two separate lifting assemblies around the BOP stack. Prior art pins are large and horizontally mounted, and are thus difficult to install and not held in place by gravity.
Thus, there remains a need for a BOP lifting apparatus that will increase the efficiency and safety of the handling of a BOP stack during rig up, rig down and transport operations. There additionally remains a need for a BOP stack lifting apparatus that can remain stable in the event of a failure or breakage in cables used in the lifting process.
The various embodiments of the present invention disclosed herein address one or more of the problems set forth above.
Certain aspects of some embodiments disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.
The present invention provides for a BOP lifting apparatus for securing and lifting a complete BOP stack. In an embodiment of the invention, the lifting apparatus is comprised of a reinforced frame and a latching gate for securing a BOP stack within the lifting apparatus. The frame has a central U-shaped recess that is sized and shaped for securing a mid-section or collared portion of the BOP stack. The gate pivotally swings between a secured, closed position on the frame and an open position for convenient installation and removal of the lifting apparatus from the BOP stack. An actuator has a first end connected to a top surface of the frame and a second end connected to the gate for actuating the opening and closing of the gate to the frame. Once the gate is moved into the closed position, one or more locking pins are inserted into pinning holes located on the gate in alignment with pinning holes located on the frame of the lifting apparatus. Upon inserting all locking pins, the lifting apparatus will securely restrain the BOP stack during transport and installation. The fully secured lifting apparatus may then itself be lifted via cables or other lifting mechanisms attached to the lifting apparatus via lifting eyelets located on the corners of the frame.
For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein. Additionally, as used herein, the term “substantially” is to be construed as a term of approximation.
Turning to
A U-shaped central recess 108 is located between sidewalls 104 and corners 106. Central recess 108 is comprised of a radiused portion 112 disposed between a pair of inner walls 110. Radiused portion 112 conforms to the contours of collared portion 202 of BOP stack 200. In a preferred embodiment, opposing parallel inner walls 110 are spaced apart at a distance no less than that of the diameter of radiused portion 112 and connect tangentially to radiused portion 112.
A pair of transition walls 114 extends between an end of each of parallel inner walls 110 and a sidewall 104 at corners 106. Transition walls 114 form an enlarged opening opposite the radiused portion 112. Transition walls 114 extend toward and terminate at corners 106.
Gate 120 is pivotally connected to a corner 106 of frame 102 via a gate pin 130. Gate 120 may be fabricated of the same material as frame 102 and is comprised of an outer wall 121 and a radiused inner wall 122 that are connected by sidewalls 123. Outer wall 121 has substantially the same length as sidewalls 104 of frame 102, but may have a height that is less than the height of the frame 102. Radiused inner wall 122 has a substantially similar radial length of that of radiused portion 112. When gate 120 is in the closed position (as shown in
Gate 120 must be significantly robust to endure the off-center lifting of the extremely heavy BOP stack 200. However, it is also important to control the opening of gate 120 to permit approach movement in closed spaces to access BOP stack 200. It is also important to be able to close gate 120 without the aid of supplemental lifting equipment, such as a forklift, when frame 102 is successfully positioned around BOP stack 200.
The closing and opening of gate 120 is accomplished by way of an actuator 150, which is pivotally connected to the top of frame 102. During opening or closing of gate 120, actuator 150 rotates a threaded rod 152 in a first direction or an opposite second direction. Threaded rod 152 has an end opposite actuator 150 that is threaded through a nut assembly 154 (shown in
Besides controlled opening and closing of gate 120, it is important to provide absolute secure lifting of BOP stack 200, even when such lifting effort is unbalanced, such as to put an unequal load on gate 120. To satisfy the requirement to provide a secure lock between gate 120 and frame 102, a series of aligned pinning holes 124, 126 and 134, 136 are located on frame 102 and gate 120, respectively, for locking with locking pins 140. More specifically, frame 102 has inner pinning holes 124 and a corner pinning hole 126 located at the intersection of a transition wall 114 and a sidewall 106. This location is opposite gate pin 130 Inner pinning holes 124 are located adjacent to each intersection of a parallel inner wall 110 with a transition wall 114, on opposite sides of the open portion of the central recess 108. Gate 120 has matching inner pinning holes 134 and at least one corner pinning hole 136. Inner pinning holes 134 are located adjacent to each intersection of the radiused inner wall 122 and sidewalls 123, with corner pinning hole 136 located on the corner of gate 120 opposite gate pin 130 Inner pinning holes 134 and corner pinning hole 136 are located such that they are aligned to the respective inner pinning holes 124 and corner pinning hole 126 when gate 120 is pivotally rotated to the closed position.
In the embodiment illustrated, the pinning holes located on frame 102 overlap the pinning holes located on gate 120. In the embodiment illustrated, when gate 120 is in the closed position, gate 120 intersects slightly into the body of frame 102 due to the height of gate 120 being less than the height of frame 102. The pinning holes located on frame 102 thus overlap and cover up the pinning holes located on gate 120. Because the height of gate 120 is unequal to the height of frame 102, the height difference would create an unbalanced lifting force on BOP stack 200 during lifting and transport. Thus, a gate pad 128 is located on top of gate 120 to provide support for BOP stack 200 over gate 120, thereby equalizing the height differential between gate 120 and frame 102.
On each corner 106 of frame 102, a lifting eyelet 160 is provided for attachment of cables or other lifting systems for lifting the apparatus 100 together with the secured BOP stack 200. Lifting eyelets 160 are located close to corners 106 to maximize stability of lifting apparatus 100 during the lifting and handling process. Ideally, at least four eyelets 160 are located equidistant from the center of frame 102 to maintain a stable platform for the lifting and handling of apparatus 100. Moreover, lifting eyelets 160 may be equidistant from adjacent eyelets 160. Lifting eyelets 160 may be integrally formed as part of frame 102, or may be separately attached to frame 102. Preferably, lifting eyelets 160 are integrally formed with frame 102 or welded onto the surface of frame 102 to maximize the strength of eyelets 160, in view of the significant stress that will be placed upon BOP lifting apparatus 100 during operation.
Turning to
During operation, the unique placement of lifting eyelets 160 on corners 106 of frame 102, as well as the unique shape of the gate 120 and placement of pinning holes 124, 126, 134, 136, results in the ability of gate 120 to remain closed even if a cable suspended from a lifting eyelet 160 were to break or otherwise become detached. That is, because the pinning holes are strategically located on gate 120 and frame 102, the connection between gate 120, frame 102 and locking pins 140 becomes tighter as lifting apparatus 100 deviates from a substantially horizontal plane.
Furthermore, due to the unique placement of lifting eyelets 160 and the overall balancing of lifting apparatus 100, even if an individual lifting point were to fail (either through detachment of a cable connected to a lifting eyelet 160, or failure of the eyelet 160 itself), the physical forces on the remaining cables and lifting eyelets 160 will be redistributed diagonally such that the three remaining lifting eyelets 160 and cables can maintain the balance of lifting apparatus 100 and BOP stack 200 without tipping and dropping it.
Dimension C defines the free passage dimension required for connection to, and release from, BOP stack 200. Dimension D defines the increase in the dimension A travel envelope when gate 120 is opened. It is critical to minimize dimension D, without weakening frame 102.
Pins 124 are located in relationship to pin holes 134 so as to minimize dimension D. An open envelope point 172 is related to a clearance point 170 on gate 120. The angle between open envelope point 172 and clearance point 170 is angle E. Minimizing angle E is achieved by the deep inset location of pins 124.
As seen in
Inside gate 120, beams 115 may extend between outer wall 121 and radiused inner wall 122, and also between outer wall 121 and a sidewall 123. In the embodiment illustrated, beams 115 are advantageously disposed between outer wall 121 and inner walls 122 proximate to the location of pin holes 134.
As described, lifting apparatus 100 is easier to bring into place and lock into place than other devices, while providing stability in the event of failure of a lifting cable. When gate 102 of lifting apparatus 100 opens, it allows BOP stack 200 to clear moving frame 102 in the horizontal plane while maintaining a minimized travel envelope as defined by dimensions A and B (
In the embodiment illustrated, one permanent vertical pin is provided at gate pin 130. The three removable vertical pins (two at 124/134, one at 126/136) are all in a parallel plane, and are all located on one side of the centerline of lifting apparatus 100. In the embodiment illustrated, with four lifting eyelets 160 located at the corners of frame 102 and gate 120, if any lift point fails, the forces will be redistributed diagonally such that the other three can maintain the hold of BOP stack 200 without tipping or dropping it.
It will be readily apparent to those skilled in the art that the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Having thus described the exemplary embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is contemplated that the appended claims will cover any such modifications or embodiments that fall within the true scope of the invention.
| Number | Date | Country | |
|---|---|---|---|
| 61799633 | Mar 2013 | US |
