Replaceable Wear Plates for Use with Blind Shear Rams
A shear ram assembly including upper and lower ram blocks having blades positioned on opposing sides of pipe and other, more ductile items, and arranged to close around and shear the pipe and the more ductile items. The shear ram assembly includes pipe guide arms attached to the upper ram block and configured to guide pipe and other items into the path of the blades, and to be received by recesses in the lower ram block. Also included are wear plates mounted on top of the pipe guide arms and positioned to force the lower ram block to rise as the arms enter the recesses, thereby causing the gap between the blades to decrease so that the blades can better shear the more ductile items.
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1. Field of the Invention
This technology relates generally to well drilling. In particular, this technology relates to a shear ram assembly for a blowout preventer (“BOP”) that has wear plates designed to adjust the relative position of ram blocks so that blades of the ram blocks can better shear ductile items, such as wireline, coiled tubings, etc.
2. Brief Description of Related Art
Offshore drilling rigs typically employ a riser to connect the subsea wellhead with the drilling rig. A BOP is located at a lower end of the riser. Land rigs also use BOPs. A BOP is a large assembly having many features for closing around a drill pipe and/or casing in the event that high pressure in the wellbore begins pushing the drilling mud upward. Those features include an annular assembly that seals around the pipe, regardless of the diameter. In addition, the BOP has pipe shear ram assemblies that will shear a drill pipe string or a production tubing string in the event of an emergency.
Pipe shear ram assemblies typically have two rams, each of which has a blade mounted to it. Pistons move the rams toward each other to shear pipe and other items extending through the BOP. Generally, one blade is located at a higher elevation than the other, and the higher blade slides over the lower blade when the shear rams close. This difference in elevation creates a gap between the blades.
One problem with known shear ram assemblies is that the blades may not shear everything in the well bore. For example, because there is a gap between the blades, items that are ductile or flexible may simply bend between the blades, rather than cut. Thus, even after the ram blocks are closed and the blades have deployed, ductile items like wiring or flexible tubing may still be intact.
SUMMARY OF THE INVENTIONDisclosed herein is a pipe shear ram assembly for use in a BOP that in one example includes upper and lower ram blocks having blades. The ram blocks are designed to be positioned on opposite sides of a well bore so that the pipe string, and other more ductile items, such as wiring, pass between the blades of the ram blocks. In the event of an emergency, the ram blocks close by moving toward one another so that the blades pass over one another. As the blades pass over one another, they shear the pipe string and other items in the wellbore, and then seal the wellbore. Generally, as the blades of the upper and lower ram blocks pass over one another, there is a vertical gap between the blades.
In an example embodiment, the pipe shear ram assembly disclosed herein includes a pair of pipe guide arms that are mounted to the upper ram block and are positioned to enter corresponding recesses in the lower ram block as the ram blocks close. In this example, the pipe shear arms are located in an outboard position relative to the blades and have a wedge-shaped inboard profile. One purpose of the pipe guide arms is to direct piping or other items located on the edges of the wellbore into the path of the blades to be cut.
Wear plates may be attached to the upper surfaces of the pipe guide arms. The wear plates are positioned so that their top surfaces are higher than the tops of the recesses on the lower ram block. As the rams blocks close, therefore, and the pipe guide arms, along with the wear plates, enter the recesses, the lower ram block is forced to rise so that the recesses can accept the wear plates. As the lower ram block rises, so does the blade attached to the lower ram block. Thus, the gap between the blades of the upper and lower ram blades is reduced. The edges of either the recesses or the wear plates may be chamfered to allow entry of the wear plates into the recesses.
The present invention will be better understood on reading the following detailed description of nonlimiting embodiments thereof and on examining the accompanying drawings, in which:
The foregoing aspects, features, and advantages of the present invention will be further appreciated when considered with reference to the following description of preferred embodiments and accompanying drawings, wherein like reference numerals represent like elements. In describing the preferred embodiments of the invention illustrated in the appended drawings, specific terminology will be used for the sake of clarity. However, the invention is not intended to be limited to the specific terms used, and it is to be understood that each specific term includes equivalents that operate in a similar manner to accomplish a similar purpose.
Referring to
In the example of
Pipe guide arms 28 are elongate members shown located on the outboard sides of upper ram block forward end 14 and projecting generally forward away from end 14. In one embodiment; the pipe guide arms 28 are similar to those disclosed in U.S. patent application Ser. No. 13/339,519, which is hereby incorporated herein by reference. Each arm 28 can be formed integrally with upper ram block 12, or can be otherwise attached, such as by welding or fasteners. Each arm 28 has a vertically oriented inboard side 30 extending forward from a base 32 of each arm 28. Base 32 is where arm 28 joins forward end 14. Each arm 28 also has a wedge surface 34 that extends from a junction with a forward end of inboard side 30 to a tip 38, and an upper surface 36. The wedge surface 34 depends laterally inward with distance away from the tip 38. As shown in
Referring again to
A lower blade 54 is attached to forward end 42 of lower ram block 40. Lower blade 54 is at a lower elevation than upper blade 18, as illustrated in
Referring to
Referring to
One advantage to the use of wear plates 52 to narrow the gap between the upper and lower blades 18, 54 is that, as shown in
Referring to
A lower marine riser package (LMRP) 88 connects to the upper end of BOP stack 76. An annular BOP 90 may be located at the lower end of LMRP 88. Annular BOP 90 will close around any size of pipe and seal the annulus between the pipe and the side wall of the bore. Annular BOP 90 will also seal fully even if a pipe is not present. A flex joint 92 is located at the upper end of LMRP 88 to allow flexing of a lower end of a riser string 94 connected to flex joint 92. Choke and kill lines 96 extend from below annular blowout preventer 90 to alongside riser 94 for pumping fluid into the well. In the event of an emergency, LMRP 88 and riser 94 can be detached from BOP stack 76. Redundant control pods 98 mount LMRP 88 and contain hydraulic and electrical circuitry for controlling movement of the various rams 10, 82, 84, 86, the annular BOP 90, and other equipment. Control pods 98 are retrievable from LMRP 88 and are connected to an umbilical (not shown) leading to the drilling vessel at the surface.
While the technology has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the technology. Furthermore, it is to be understood that the above disclosed embodiments are merely illustrative of the principles and applications of the present technology. Accordingly, numerous modifications may be made to the illustrative embodiments and other arrangements may be devised without departing from the spirit and scope of the present technology as defined by the appended claims.
Claims
1. A shear ram assembly for shearing a pipe and ductile items, comprising:
- first and second ram blocks positioned adjacent the pipe and ductile items, and on opposite sides thereof, the first and second ram blocks arranged to close around the pipe and ductile items;
- first and second blades attached respectively to the first and second ram blocks and positioned so that as the first and second ram blocks close around the pipe and the ductile items, the blades pass over one another and shear the pipe and the ductile items;
- at least one recess in the second ram block;
- at least one arm attached to the first ram block that inserts into the at least one recess when the first and second ram blocks close; and
- at least one plate positioned on the at least one arm, so that when the arm inserts in to the at least one recess, the wear plate slides against a surface of the recess and orients the blades at a maximum distance apart.
2. The shear ram assembly of claim 1, wherein the blades are separated by a distance of about 0.003 inch to about 0.008 inch when closed.
3. The shear ram assembly of claim 1, wherein the wear plates are attached to the arms by a means selected from the group consisting of welding, adhering, and fastening with mechanical fasteners.
4. The shear ram assembly of claim 1, wherein a distance from a lower surface of the first blade to an upper surface of the wear plate exceeds a distance from a lower facing surface of the recess to an upper surface of the second blade by a designated amount.
5. The shear ram assembly of claim 1, wherein the edges of the recesses are chamfered to allow the wear plates to enter the recesses as the upper and lower ram blocks close.
6. The shear ram assembly of claim 1, wherein the edges of the wear plates are chamfered to allow the wear plates to enter the recesses as the upper and lower ram blocks close.
7. The shear ram assembly of claim 1, wherein the blade of the upper ram block is attached to a forward end of the upper ram block, and has a face, an upper edge, and a lower edge, and wherein the lower edge extends farther forward from the forward end than the upper edge, so that the face is inclined relative to the forward end of the upper ram block.
8. The shear ram assembly of claim 7, wherein the blade of the upper ram block has outboard ends that extend farther forward from the forward end than a central portion of the blade, so that the face of the blade has a generally concave configuration.
9. The shear ram assembly of claim 1, wherein the arms are attached to the upper ram block by means selected from the group consisting of welding, adhering, and mechanical fasteners.
10. The shear ram assembly of claim 1, wherein the arms are integral with the upper ram block.
11. A shear ram assembly for shearing a pipe and ductile items, comprising:
- first and second ram blocks, each having a blade, and the second ram block defining a recess positioned laterally with respect to the blades, the first and second ram blocks positioned on opposite sides of the pipe and the ductile items, and such that one slides over the other when the first and second ram blocks are moved forward to a closed position, thereby shearing the pipe and the ductile items;
- a guide arm protruding from the first ram block toward the second ram block and positioned to enter the recess when the first and second ram blocks close, and
- a wear plate attached to an upper surface of each guide arm that selectively engages an upper surface of the recess to raise the second ram block upward relative to the first ram block so that any gap between the blades is reduced.
12. The shear ram assembly of claim 11, wherein the gap between the blades is about 0.003 inch to about 0.008 inch when closed.
13. The shear ram assembly of claim 11, wherein the wear plates are attached to the arms by a means selected from the group consisting of welding, adhering, and fastening with mechanical fasteners.
14. The shear ram assembly of claim 11, wherein the wear plates are integral with the arms.
15. The shear ram assembly of claim 11, wherein the edges of the recesses are chamfered to allow the wear plates to enter the recesses as the upper and lower ram blocks close.
16. The shear ram assembly of claim 11, wherein the edges of the wear plates are chamfered to allow the wear plates to enter the recesses as the upper and lower ram blocks close.
17. The shear ram assembly of claim 11, wherein the arms are attached to the upper ram block by means selected from the group consisting of welding, adhering, and mechanical fasteners.
18. The shear ram assembly of claim 11, wherein the arms are integral with the upper ram block.
19. A subsea BOP assembly, comprising:
- a BOP stack having a frame with a wellhead connector at a lower end for connecting to a subsea wellhead assembly; and
- at least one shear ram attached to the frame for shearing pipe and ductile items extending through the BOP assembly and into the wellhead assembly, the at least one shear ram comprising: first and second ram blocks positioned adjacent the pipe and ductile items, and on opposite sides thereof, the first and second ram blocks arranged to close around the pipe and ductile items; first and second blades attached respectively to the first and second ram blocks and positioned so that as the first and second ram blocks close around the pipe and the ductile items, the blades pass over one another and shear the pipe and the ductile items; at least one recess in the second ram block; at least one arm attached to the first ram block that inserts into the at least one recess when the first and second ram blocks close; and at least one plate positioned on the at least one arm, so that when the arm inserts in to the at least one recess, the wear plate slides against a surface of the recess and orients the blades at a maximum distance apart.
Type: Application
Filed: Aug 16, 2012
Publication Date: Feb 20, 2014
Applicant: HYDRIL USA MANUFACTURING LLC (Houston, TX)
Inventors: Elliot Thomas Yendell (Cypress, TX), Viral Shah (Houston, TX)
Application Number: 13/587,670
International Classification: E21B 29/00 (20060101); E21B 33/06 (20060101);