MX2015002041A - Replaceable wear plates for use with blind shear rams. - Google Patents

Abstract

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.

Description

REPLACEABLE WEAR PLATES FOR USE WITH SHEAR ARIES BLIND FIELD OF THE INVENTION This technology is usually related to well drilling. In particular, this technology is related to a shear ram assembly for an explosion preventer ("BOP") that has wear plates designed to adjust the relative position of the ram blocks so that the blades of the ram blocks They can better shear ductile items, such as cables, rolled pipes, etc.

ANTECEDENTS OF THE INVENTION Offshore drilling rigs employ an elevator to connect the underwater wellhead to the drilling rig. A BOP is located at a lower end of the elevator. Terrestrial platforms also use BOP. A BOP is a large assembly that has many features to close around a drill pipe and / or enclose it in case the high pressure in the well begins to push the drilling mud up. These features include an annular assembly that is sealed around the tube, regardless of diameter. In addition, the BOP has tube shear ram assemblies that will shear a drill pipe chain or production line chain in case of an emergency.

Pipe shear ram assemblies typically have two rams, each of which has a blade mounted on it. The pistons move the rams toward each other to shear the tube and other items that extend through the BOP. Generally, one blade is located at a higher elevation than the other, and the highest blade slides over the lower blade when the shear rams close. This difference in elevation creates an empty space between the blades.

A problem with known shear ram assemblies is that the blades may not shear all in the well. For example, because there is an empty space between the blades, articles that are ductile or flexible can simply be folded between the blades, instead of being cut. Thus, even after the water hammer blocks are closed and the blades have been unfolded, the ductile articles such as cables or flexible tubing may still be intact.

BRIEF DESCRIPTION OF THE INVENTION Herein is disclosed a tube shear ram assembly for use in a BOP which in one example includes upper and lower ram blocks having blades. The water hammer blocks are designed to be positioned on opposite sides of a well, so that the pipe chain, and other more ductile items, such as cables, pass between the blades of the water hammer blocks. In the case of an emergency, the water hammer blocks are closed moving towards each other so that the blades pass one on top of the other. While the blades pass one on top of the other, they shear the pipe chain and other items in the well, and then seal the well. Generally, while the blades of the upper and lower ram blocks pass one on top of the other, there is a vertical void space between the blades.

In an exemplary embodiment, the tube shear ram assembly disclosed herein includes a pair of tube guide arms that are mounted to the upper ram block and are positioned to enter the corresponding recesses in the lower ram block while the ram blocks close. In this example, the tube shear rams are located in an outboard position relative to the blades and have an internal wedge-shaped profile. One purpose of the tube guide arms is to direct the pipe or other articles located on the edges of the well in the path of the blades to be cut.

The wear plates can be attached to the upper surfaces of the tube guide arms. The wear plates are positioned so that their upper surfaces are higher than the upper parts of the recesses on the lower ram block. While the water hammer blocks are closed, therefore, and the tube guide arms, together with the wear plates, enter the recesses, the lower ram block is forced to rise so that the recesses can accept the wear plates. While the lower ram block is raised, so does the blade attached to the lower ram block. This reduces the gap between the blades of the upper and lower ram blades. The edges of either the recesses or the wear plates can be bevelled to allow the wear plates to enter the recesses.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood by reading the following detailed description of non-limiting embodiments thereof, and by examining the accompanying drawings, in which: Figure 1 is a perspective view of the water hammer blocks of a shear ram assembly according to this disclosure; Figure 1A is a perspective view of the ram blocks of Figure 1, with the ram blocks substantially closed around the tube and the ductile articles; Figure 2 is a side view of the ram blocks of Figure 1; Figure 3 is a bottom perspective view of the ram blocks of Figure i; Figure 4 is a front view of the upper ram block of Figure 1; Figure 5 is a top view of the upper ram block of Figure 1; and Figure 6 is a perspective view of the water blocks of Figure 1 installed within a subsea BOP assembly.

DETAILED DESCRIPTION OF THE INVENTION The above aspects, features and advantages of the present invention will be further appreciated when considered with reference to the following description of the preferred embodiments and the accompanying drawings, in which like reference numerals represent similar elements. In describing the preferred embodiments of the invention illustrated in the accompanying drawings, specific terminology will be used for purposes 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 achieve a similar purpose.

With reference to Figure 1, the shear rams 10 are shown removed from the housing or cover (not shown) where they are located. The shear arms 10 are part of a ram BOP assembly that is part of a stacking assembly. In the case of offshore drilling, the stacking assembly is located at the lower end of an elevator that extends down from a drill ship. The lower end of the BOP stacking assembly will typically also contain pipe rams, variable auger rams, and a quick disconnect mechanism to disconnect from the elevator in an emergency. When actuated, the shear rams 10 will be closed through the bore and also the shear tube and other items in the well, such as, for example, drill pipe, pipe, casing or wiring.

In the example of Figure 1, the shear rams 10 include a generally flat upper ram block 12 having a side surface defining a front face or end 14. A semicircular groove 16 is located on the upper side of the ram block. 12 to receive a portion of an elastomeric seal. An upper shear blade 18 is mounted to the front end 14 by means of appropriate means, as, for example, by means of fasteners 74. The upper blade 18 has a front face 20 with an upper edge 22 and a lower edge 24. For purposes of this disclosure, the front term, with reference to the Water hammer blocks and associated components, should mean in a lateral direction from the face 20 and away from the end 14. In the example of Figure 1, the lower edge 24 extends further forward from the leading end 18 than the upper edge 22, which results in the face 20 tilting in relation to the leading end 14. The face 20 is also generally concave or convergent, which results in the center of the face 20 between its outboard ends 26 being recessed in relation to the forward portions of the face 20 at the outboard ends 26. A variety of different shapes can be employed for the upper blade 18.

The tube guide arms 28 are shown elongated members located on the outboard sides of the forward end of the upper ram block 14 and projecting generally forwardly away from the end 14. In an embodiment, the tube guide arms 28 are similar to those disclosed in US Pat. No. 13 / 339,519, which is hereby incorporated by reference herein. Each arm 28 can be formed integrally with the upper ram block 12, or else it can be attached, by means of welding or fasteners. Each arm 28 has a vertically oriented inner side 30 extending forward from a base 32 of each arm 28. The base 32 is where the arm 28 joins the leading end 14. Each arm 28 has a wedge surface 34 extending from a junction with a leading end of the inner side 30 with a tip 38 and an upper surface 36. The wedge surface 34 laterally inwardly depends with the distance away from the tip 38. As shown in Figure 2, the upper surface 36 is spaced at a lower elevation above the front end of upper ram block 14 to the lower edge of upper blade 24. The upper surface 36 is not located directly under the upper blade 18 in this example because the inner side 30 of each arm 28 is approximately the same outboard distance as that of the outboard end of upper blade 26, as shown, for example, in Figure 5. Also, the FIGS. 2 and 5 illustrate that the tip 38 extends forward more than the upper blade 18 of the front end 14. The junction of the inner side 30 with the wedge surface 34 is approximately in vertical alignment with the attachment of the upper edge of the blade. upper shear 22 and the outboard end 26. One purpose of the arms 28 is to guide a tube (not shown) and other more ductile articles in an interior direction towards the blades. A wear plate 52 is optionally attached to the upper surface of each arm 28, as discussed in more detail below.

Referring again to Figure 1, there is illustrated a substantially flat lower ram block 40 in horizontal alignment with the upper ram block 12. The lower ram block 40 has a front end 42 which is parallel to the front end 14 of the upper ram 12. An upper seal groove 44 on the upper side of lower ram block 40 receives an elastomeric seal and aligns with seal groove 16 to form a continuous seal when the ram blocks 12, 40 are spliced together. The seal is not necessarily circular. On its upper surface, the lower ram block 40 has a sheared tube end recess 46 for receiving the lower end of the well tube and the ductile articles after the shear. The sheared tube end recess 46 has a curved rear wall portion 48 that is blended with two straight side wall portions 50. Other shapes are feasible.

A Lower blade 54 is connected to the front end 42 of the lower ram block 40. The lower blade 54 is at a lower elevation than that of the upper blade 18, as illustrated in Figure 2. The blade 54 slides under the the upper blade 18 when there is shear. An upper edge 56 of the lower blade 54 is at a slightly lower elevation than the lower edge 24 of the upper blade 18. The lower blade 54 has a lower edge 58 that is closer to the front end 42 of the lower block than the edge upper 56. A face 60 extends between the lower edge 58 and the upper edge 56 and thus slopes in relation to the front end 42. As illustrated in Figure 2, in this example, the inclination of the lower knife face 60 is the same as the inclination of the upper knife face 20. The lower knife face 60 also embeds or converges with a central area that is closer to the lower block front end 42 than the outboard ends 62 of the lower blade 54, as shown in Figure 1. The length of lower blade 54 from one outboard end 62 to the other is the same as the length of upper blade 18 from one end was from board 26 to the other.

With reference to Figure 3, which shows the bottom of the shear rams 10, a recess 64 is located on the lower shear block 40 along each outboard side and towards the rear from the ends outside of the outer shear block. bottom blade embroidery 62. Each recess 64 has a space or clearance provided along an outboard side to receive one of the arms 28 when the ram blocks 12, 40 are closed. Each recess 64 is defined by a downward facing top side wall 66 and an interior side wall 68, the side walls 66 and 68 are flat and perpendicular in this example. Each recess 64 is aligned with one of the arms 28 to receive the arm when in the closed or sheared position. Each recess 64 has a length greater than the length of each arm 28. Also, the upper side wall 66 has a width greater than that of each arm 28, and the inner side wall 68 has a height greater than the height of each arm 28. The recess 64 need not be a closed cavity, and in the example shown it does not have an outboard side wall or a bottom side wall.

With reference to Figures 1 and 2, the wear plates 52 may be joined with the arms 28 in any appropriate manner, such as, for example, welding, adhesion or mechanical fasteners. In an alternative embodiment, the wear plates 52 can be formed integrally with the arms 28. Each wear plate 52 has a sufficient thickness so that the top 70 of each wear plate 52 is slightly greater than the upper side wall 66 of the recesses 64 when the ram blocks 12, 40 are open. Thus, when the ram blocks 12, 40 are closed, the wear plate 52 comes into contact with the upper side wall 66 of the recess 64 and forces the lower ram block 40 to rise. While the lower ram block 40 is raised, the lower blade 54 is raised in relation to the upper blade 18, so that the vertical void space between the blades 18, 54 is reduced. A leading edge 72 of the recess 64 is bevelled (as shown in Figures 2 and 3) to enable the wear plate 52 to slide into the recess 64 while the ram blocks 12, 40 close. Alternatively, the leading edge of the wear plate may be bevelled for the same purpose. In yet another embodiment, the arms 28 can be positioned so that the upper surface 36 of the same arms 28 makes contact with the upper side wall 66 of the recess 64, thereby forcing the raising of the ram block 40. In such mode, the 52 wear plates may not be necessary.

Figure 1A shows the upper and lower ram blocks 12, 40 in a substantially closed position around the tube 100 and the ductile articles 102, such as, for example, flexible piping or wiring. The arms 28, including the wear plates 52, are shown partially engaged with the recess 64. As can be seen, the upper and lower blades 18, 54 have passed substantially one above the other, shearing both the tube 100 and the ductile articles 102.

An advantage of the use of the wear plates 52 for narrowing the gap between the upper and lower blades 18, 54 is that, as shown in Figure 1A, the rams 12, 40 can better shear the ductile articles. For example, in embodiments that do not include the wear plates 52, vertical compensation between the upper end 56 of the lower knife 54 and the lower end 24 of the upper knife 20 may be large enough so that the ductile articles do not cut, but merely bend, or flex, in the empty space between the blades while the blades close. However, with the wear plates 52 in place, as shown in Figure 1A, the empty space between the blades decreases substantially so that even the ductile articles will be cut, as there is no room to bend. In an exemplary embodiment, the vertical distance between the upper end 56 of the lower knife 54 and the lower end 24 of the upper knife 20 when the wear plates 52 are not in place is approximately 0.0508 cm. Conversely, in embodiments with the wear plates 52, the vertical compensation between the blades is reduced to a range of less than about 0.0508 cm, and in the range of about 0.0076 cm or less to about 0.0203 cm.

Figure 4 is a front view of the upper ram 12 in accordance with a modality of the present technology. In particular, Figure 4 shows wear plates 52 attached to the upper surface 36 of each arm 28. Figure 5 similarly shows a top view of the upper ram 12 having wear plates 52 attached to the arms 28. The Figures 4 and 5 also show the position of the arms 28 in relation to the blade 18 of the upper ram 12. For example, Figures 4 and 5 show that the wear plates 52 are positioned laterally to the upper ram blade 18 of FIG. so as not to interfere with the trajectory of the blade 18 while the rams 12, 40 are closed. Although the wear plates 52 are shown to be rectangular in shape, they may alternately have a different shape, as long as the top 70 of each plate wear 52 is configured to make contact with the upper side wall 66 of the recess 64 and raise the lower ram block 40 relative to the upper ram block 12 as described in FIG. earlier.

With reference to Figure 6, shear rams 10 are shown installed in a typical subsea BOP assembly. The BOP assembly has a BOP stack 76 which includes a frame 78 with a wellhead connector 80 at the lower end for connection to an underwater wellhead assembly (not shown). The shear rams 10 are usually located above the tube rams, which in this example include tube rams 82, 84 and 86. Each tube rams 82, 84 and 86 have rams with semi-cylindrical recesses on the contact faces. to close around a different tube size range. When closed, the shear rams 10 will seal the drill and if the tube and / or other items are present, they will shear the tube and other items.

A lower marine riser package (LMRP) 88 connects to the upper end of the BOP 76 stack. An annular BOP 90 may be located at the lower end of the LMRP 88. The annular BOP 90 will close around any size of tube and seal the ring between the tube and the side wall of the drill. The annular BOP 90 will also be completely sealed even if a tube is not present. A flexible link 92 is located at the upper end of the LMRP 88 to allow flexing of a lower end of an elevator chain 94 connected to the flexible link 92. The choke and drown lines 96 extend from below the annular explosion preventer. 90 towards the side of the elevator 94 to pump fluid into the well. In case of emergency, the LMRP 88 and the elevator 94 can be detached from the BOP stack 76. The redundant control pods 98 assemble the LMRP 88 and contain hydraulic and electrical circuits to control the movement of the various rams 10, 82, 84, 86, BOP 90 annular and other equipment. The control pods 98 can be recovered from the LMRP 88 and are connected to an umbilical (not shown) leading to the drill ship on the surface.

Although the technology has been shown or described only in some of its forms, it should be apparent to those skilled in the art that it is not limited, but is susceptible to several changes without departing from the scope of the technology. Additionably, it is to be understood that the embodiments described above are merely illustrative of the principles and applications of the present technology. Accordingly, numerous modifications may be made to the illustrative embodiments and other provisions may be devised without departing from the spirit and scope of the present technology as defined in the appended claims.

Claims (19)

NOVELTY OF THE INVENTION CLAIMS

1. - A shear ram assembly for shearing a pipe and ductile articles, comprising: first and second ram blocks positioned adjacent to the pipe and the ductile articles, and on opposite sides thereof, the first and second blocks of ram arranged for closing around the tube and ductile articles; first and second blades joined respectively to the first and second ram blocks and positioned so that the first and second ram blocks close around the pipe and the ductile articles, the blades pass one on top of the other and shear the pipe and the ductile articles; at least one recess in the second ram block; at least one arm connected to the first ram block that is inserted into the at least one recess when the first and second ram blocks are closed; and at least one plate positioned on the at least one arm, so that when the arm is inserted into the at least one recess, the wear plate slides against a surface of the recess and orientates the blades apart at a maximum distance.

2. - The shear ram assembly according to claim 1, further characterized in that the blades are separated by a distance of approximately 0. 0076 cm to approximately 0.0203 cm when closed.

3. - The shear ram assembly according to claim 1, further characterized in that the wear plates are joined with the arms with means selected from the group consisting of welding, adhesion and fastening with mechanical fasteners.

4. The shear ram assembly according to claim 1, further characterized in that a distance from a lower surface of the first blade to an upper surface of the wear plate exceeds a distance from a lower face surface of the recess to a surface of the second blade by means of a designated amount.

5. The shear ram assembly according to claim 1, further characterized in that the edges of the recesses are bevelled to allow the wear plates to enter the recesses while the upper and lower ram blocks are closed.

6. The shear ram assembly according to claim 1, further characterized in that the edges of the wear plates are beveled to allow the wear plates to enter the recesses while the upper and lower ram blocks are closed.

7. - The shear ram assembly according to claim 1, further characterized in that the blade of the upper ram block is joined with a front end of the upper ram block, and has a face, an upper edge and a lower edge, and wherein the lower edge extends further forward from the end front than the upper edge, so that the face is tilted relative to the front end of the upper ram block.

8. - The shear ram assembly according to claim 7, further characterized in that the blade of the upper ram block has outboard ends that extend further 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 according to claim 1, further characterized in that the arms are joined with the upper ram block with means selected from the group consisting of welding, adhesion and mechanical fasteners.

10. - The shear ram assembly according to claim 1, further characterized in that the arms are integral with the upper ram block.

11. - A shear ram assembly for shearing a pipe and ductile articles, 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 tube and the articles ductile, and so that one slides on the other when the first and second blocks of ram move forward towards a closed position, thus shearing the pipe and the ductile articles; a guide arm projecting from the first ram block into the second ram block and positioned to enter the recess when the first and second ram blocks are closed, and a wear plate attached with an upper surface of each guide arm which selectively engages a top surface of the recess to raise the second ram block upwardly relative to the first ram block so as to reduce any empty space between the blades.

12. The shear ram assembly according to claim 11, further characterized in that the empty space between the blades is from about 0.0076 cm to about 0.0203 cm when closed.

13. - The shear ram assembly according to claim 11, further characterized in that the wear plates are joined with the arms with means selected from the group consisting of welding, adhesion and fastening with mechanical fasteners.

14. - The shear ram assembly according to claim 11, further characterized in that the wear plates are integral with the arms.

15. - The shear ram assembly according to claim 11, further characterized in that the edges of the recesses are beveled to allow the wear plates to enter the recesses while the upper and lower ram blocks are closed.

16. The shear ram assembly according to claim 11, further characterized in that the edges of the wear plates are beveled to allow the wear plates to enter the recesses while the upper and lower ram blocks are closed.

17. - The shear ram assembly according to claim 11, further characterized in that the arms are joined with the upper ram block with means selected from the group consisting of welding, adhesion and mechanical fasteners.

18. - The shear ram assembly according to claim 11, further characterized in that the arms are integral with the upper ram block.

19. - A submarine BOP assembly, comprising: a BOP stack having a frame with a wellhead connection at a lower end for connection to a submarine wellhead assembly; and at least one shear ram attached to the frame for shearing the tube and the ductile articles extending through the BOP assembly and into the wellhead assembly, the at least one shear ram comprises: first and second blocks of ram positioned adjacent to the pipe and the ductile articles, and on opposite sides thereof, the first and second ram blocks arranged to close around the pipe and the ductile articles; first and second blades joined respectively to the first and second ram blocks and positioned so that the first and second ram blocks close around the pipe and the ductile articles, the blades pass one on top of the other and shear the pipe and the ductile articles; at least one recess in the second ram block; at least one arm connected to the first ram block that is inserted into the at least one recess when the first and second ram blocks are closed; and at least one plate positioned on the at least one arm, so that when the arm is inserted into the at least one recess, the wear plate slides against a surface of the recess and orientates the blades apart at a maximum distance.