NON-SEALING CASING SHEAR RAMS

Abstract

Non-sealing casing shear rams are utilized in a blow out preventer (BOP) for shearing or cutting casing, but do not seal. The BOP with non-sealing casing shear rams with V-shaped blades has the shearing capabilities of a larger shear ram BOP while utilizing a smaller sized BOP to reduce the need for additional time, expense, and equipment. The non-sealing casing shear ram BOP may be used for drilling operations and during production without the need for swapping a larger shear ram BOP used for drilling to a smaller shear ram BOP for operations. The V-shape blade and back rake angle of the non-sealing casing shear ram blades produce the shearing force of the larger BOP in a smaller sized BOP.

Claims

1. Upper and lower non-sealing casing shear rams for use in a BOP comprising an opening through said BOP, comprising: said upper and lower non-sealing casing shear rams each comprising V-shaped ram cutter blades, said V-shaped ram cutter blades comprising an angle of a V shape of said V-shaped ram cutter blades between 7? degrees and 45 degrees with respect to a diameter line through said opening; said upper and lower non-sealing casing cutter blades each comprising a back rake angle between 7 degrees and 25 degrees with respect to a coaxial line through said opening; and said V-shaped ram cutter blades being configured to close and completely cut a pipe in said opening wherein an outer diameter of said pipe is at least 25% less than a diameter of said opening through said BOP.

2. The upper and lower non-sealing casing shear rams of claim 1, wherein said angle of said V shape is between 30 and 40 degrees and said back rake angle is between 15 degrees and 35 degrees.

3. The upper and lower non-sealing casing shear rams of claim 1, wherein said angle of said V shape is between 33 and 38 degrees and said back rake angle is between 15 degrees and 25 degrees.

4. The upper and lower non-sealing casing shear rams of claim 1, wherein said angle of said V shape is 35 degrees and said back rake angle is 20 degrees.

5. The upper and lower non-sealing casing shear rams of claim 1, wherein said angle of said V-shape is identical for said upper and lower non-seal casing shear rams.

6. The upper and lower non-sealing casing shear rams of claim 5, wherein said back rake angle is the same for said upper and lower non-seal casing shear rams.

7. The upper and lower non-sealing casing shear rams of claim 5, wherein said V-shaped ram cutter blade for said upper non-sealing casing shear ram is a mirror image of said V-shaped ram cutter blade for said lower non-sealing casing shear ram.

8. The upper and lower non-sealing casing shear rams of claim 1 further comprising said upper and lower non-sealing casing shear rams being operable to shear casing at least 9? inches diameter wherein said BOP having a diameter of 13? inches.

9. The upper and lower non-sealing casing shear rams of claim 1 wherein said V-shaped ram cutter blades being configured to close and completely cut a pipe in said opening wherein an outer diameter of said pipe is at least between 25% and 30% less than a diameter of said opening through said BOP.

10. Upper and lower non-sealing casing shear rams for use in a BOP comprising an opening through said BOP, comprising: said upper and lower non-sealing casing shear rams each comprising V-shaped ram cutter blades, said V-shaped ram cutter blades comprising an angle of a V shape of said V-shaped ram cutter blades between 7? degrees and 45 degrees with respect to a diameter line through said opening; said upper and lower non-sealing casing shear rams being wider in diameter than said opening of said BOP; said upper and lower non-sealing casing shear cutter blades each comprising a back rake angle between 7 degrees and 25 degrees with respect to a coaxial line through said opening; said V-shaped ram cutter blades being configured to close and completely cut a pipe in said opening wherein an outer diameter of said pipe is at least 25% less than a diameter of said opening through said BOP; and said upper and lower non-sealing casing shear rams each having no seals.

11. The upper and lower non-sealing casing shear rams of claim 10 further comprising said upper and lower non-sealing casing shear rams being operable to shear casing up to 9? diameter wherein said BOP having a diameter of 13?.

12. The upper and lower non-sealing casing shear rams of claim 10 wherein said angle of said V shape is between 30 and 40 degrees and said back rake angle is between 15 degrees and 35 degrees.

13. The upper and lower non-sealing casing shear rams of claim 10, wherein said angle of said V shape is between 33 and 38 degrees and said back rake angle is between 15 degrees and 25 degrees.

14. The upper and lower non-sealing casing shear rams of claim 10, wherein said angle of said V shape is 35 degrees and said back rake angle is 20 degrees.

15. The upper and lower non-sealing casing shear rams of claim 10, wherein said angle of said V-shape is identical for said upper and lower non-seal casing shear rams.

16. The upper and lower non-sealing casing shear rams of claim 10, wherein said rake angle is the same for said upper and lower non-seal casing shear rams.

17. The upper and lower non-sealing casing shear rams of claim 10, wherein said V-shaped ram cutter blade for said upper non-sealing casing shear ram is a mirror image of said V-shaped ram cutter blade for said lower non-sealing casing shear ram.

18. The upper and lower non-sealing casing shear rams of claim 10 wherein said V-shaped ram cutter blades being configured to close and completely cut a pipe in said opening wherein an outer diameter of said pipe is at least between 25% and 30% less than a diameter of said opening through said BOP.

19. The upper and lower non-sealing casing shear rams of claim 10 further comprising said upper and lower non-sealing casing shear rams being operable to shear casing at least 9? inches diameter wherein said BOP having said opening being a diameter of 13? inches.

20. Upper and lower non-sealing casing shear rams for use in a BOP comprising an opening through said BOP, comprising: Upper and lower non-sealing casing shear rams for use in a BOP comprising an opening through said BOP, comprising: said upper and lower non-sealing casing shear rams each comprising V-shaped ram cutter blades, said V-shaped ram cutter blades comprising an angle of a V shape of said V-shaped ram cutter blades between 7? degrees and 45 degrees with respect to a diameter line through said opening; said upper and lower non-sealing casing cutter blades each comprising a back rake angle between 7 degrees and 25 degrees with respect to a coaxial line through said opening; and said V-shaped ram cutter blades being configured to close and completely cut a pipe in said opening wherein an outer diameter of said pipe is at least 70% of a diameter of said opening through said BOP.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above general description and the following detailed description are merely illustrative of the generic invention. Additional modes, advantages, and particulars of this invention will be readily suggested to those skilled in the art without departing from the spirit and scope of the invention. A more complete understanding of the invention and many of the attendant advantages thereto will be readily appreciated by reference to the following detailed description when considered in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts and wherein:

[0015] FIG. 1 is a perspective view of a non-sealing casing shear ram assembly with shear rams in a closed position in accord with one embodiment of the present invention;

[0016] FIG. 2 is a perspective view of a non-sealing casing shear ram assembly with shear rams in an open position in accord with one embodiment of the present invention;

[0017] FIG. 3 is a cut away perspective view of a non-sealing casing shear ram assembly with shear rams in open position in accord with one embodiment of the present invention;

[0018] FIG. 4 is a cut away perspective view of a non-sealing casing shear ram assembly with shear rams in a closed position in accord with one embodiment of the present invention;

[0019] FIG. 5 is a top view of a non-sealing casing shear ram assembly with shear rams engaged with casing in a borehole in accord with one embodiment of the present invention;

[0020] FIG. 6 is a cut away perspective view of a non-sealing casing shear ram assembly with shear rams engaged with casing in a borehole in accord with one embodiment of the present invention;

[0021] FIGS. 7A-D show several views of an upper body shear ram in accord with one embodiment of the present invention;

[0022] FIGS. 8A-D show several views of a lower body shear ram in accord with one embodiment of the present invention.

DETAILED DESCRIPTION

[0023] Detailed descriptions of the invention are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or manner.

[0024] Shearing ram BOPs that are 13? are widely available with the capability of shearing 6? tubulars. However, the capability to shear 9? casing with a 13? BOP is not currently possible with prior art BOP shear rams. This is because prior art BOPs that have the shear rams with the capability of shearing 9? casings are larger than 13? such as 18? BOPs which increases the complexity of the BOP stack to be used. This in turn results in an increase in the overall cost and time necessary to install for drilling operations.

[0025] Looking now to FIGS. 1 and 4, perspective views are shown of a non-sealing casing shear ram assembly BOP 100 with upper and lower non-sealing casing shear rams 2,4 in a closed position in accord with one embodiment of the present invention. The non-sealing casing shear ram BOP 100 can shear 9? casing with a 13? BOP by utilizing non-sealing shear rams 2,4. The BOP 100 may have flanges 22 for mounting with a bore or opening 6 passing therethrough. The rams 2,4 cover the entire bore 6 to provide the maximum shearing force within the said size BOP 100. The blades 10, 12 cover the entire range of the bore 6 (See FIG. 5). The rams 2,4 are V-shaped and cover the entire bore. In this way, they center the pipe, casing, tubular, or the like 8 relative the shear blades 10,12 even when the pipe is touching one side of the interior diameter of bore 6 through the BOP. Once the pipe 8 is centered, the rams 2,4 are then energized by the actuators or the like to cut the pipe 8.

[0026] Upper shear ram 2 and lower shear ram 4 are complementary whereby both rams 2,4 are the same size and shape. The upper shear ram 2 engages or slips over lower shear ram 4 during closing operations. The V-shape of the upper blade 10 and lower blade 12 assist to guide or urge a tubular or casing 8 (see FIG. 5, 6) centrally in the bore 6.

[0027] Looking to FIGS. 2-3, perspective views are shown of a non-sealing casing shear ram assembly BOP 100 with shear rams 2,4 in an open position in accord with one embodiment of the present invention. In the open position, the upper shear ram 2 and lower shear ram 4 are retracted and positioned away from the bore 6 in the ram cavity 18 within ram body 20. Additionally, after closing and shearing of a tubular or casing 8, the upper shear ram 2 and lower shear ram 4 may be retracted to the open position. As shown, after shearing the casing 8, the casing 8 (see FIG. 5, 6) may be crimped, pinched, or the like such that casing 8 is relatively flattened so that excess or uncontrolled fluid does not escape from the casing 8. Furthermore, in a preferred embodiment, due to the upper and lower shear rams 2,4 size spanning across the entire diameter in the ram bore 6, seals are not included within the rams 2,4 and therefore the rams do not seal after shearing. There is no room for seals because the V-shaped upper and lower blades span the entire diameter of the ram cavity

[0028] Turning to FIGS. 5-6, a top view and perspective view is shown of a non-sealing casing shear ram assembly 100 with shear rams 2,4 engaged with casing 8 in a borehole 6 in accord with one embodiment of the present invention. The shear rams 2,4 have a larger blade length as compared to standard V-shaped shear ram blades. The blades 10, 12 span the entire bore 6 to capture the entire bore area. The blade's 10,12 geometry urges pipe 8 into the center [0029] of bore 6 prior to shearing to ensure complete shearing of the pipe 8 within the bore 6. The double V-shear (DVS) rams have an upper and lower blade 10, 12. The rams 2, 4 are larger than the bore 6 thereby providing the maximum force to shear the pipe 8 within the bore 6. The shear ram blade 10, 12 have a back rake angle 16 which shears, breaks, or cuts the pipe 8 due to the tension of the rake angle 16 placed upon the pipe 8.

[0030] As can be seen in FIGS. 5-6, a casing 8, pipe, tubular, or the like may be offset from the center of the bore 6. This may occur during standard drilling operations as the pipe is moved along during such operations. During the oil drilling operation any failures of pressure control equipment may require blowout preventers (BOPs) to activate to prevent incidents which might otherwise result in death, injury, and/or oil spills that may have a substantial impact on the environment and others. A blowout preventer, such as the non-sealing case shearing ram BOP 100, may be activated to prevent a catastrophic failure. These BOPs are devices that are utilized to close off the wellbore in an emergency to prevent formation fluid from reaching the surface of the well. In a blowout preventer stack, the drill string may be sheared through casing or any other tubing when they are in the wellbore. During this operation, it is imperative that casing 8 is sheared completely. Therefore, the maximum shearing capability is required. To assist in obtaining maximum cutting force, centering the pipe within the blades 10, 12 is important. In this way, the shape of the cutting blade of the rams and the area of the rams can provide the maximum shearing force. The blades 10, 12 have V angles 14 which urge the tubular 8 into the center of the bore 6 as the upper and lower shear rams 2, 4 are driven towards the bore 6 into the closed position as suggested in FIG. 5, 6. As the blades overlap, the casing is sheared as can be best seen in FIG. 4. Bore 6 may also be referred to as the nominal bore opening.

[0031] Moving to FIGS. 7A-D and FIGS. 8A-D, several views are shown of an upper body shear ram 2 and lower shear ram 4, respectively, in accord with one embodiment of the present invention. The upper and lower non-sealing casing shear rams and blades are complementary of each other. In other words, they are mirror images to each other respectively. The blade geometry is an important aspect in order to achieve the requisite shearing force. The blades 10, 12 have a blade profile with back rake angles 16 which flatten and expand the casing 8 as it is being cut so that the cut casing is then closed off. The fluid is not released within the atmosphere of the bore due to the casing being closed. No seals are necessary and therefore are removed from the rams to maximize the space available for the rams within the BOP 100. Therefore, the entire ram cavity 18, which is larger than the diameter 6, is filled with the shear rams 2, 4 not allowing clearance for seals. Thus, this provides the shear rams 2, 4 to have the advantage of cutting 9? casing while using 13? BOPs which is not possible with prior art BOPs. This in turn reduces the overall time and cost required because prior art drilling operations need to use a larger shear ram BOP, such as 18? , to cut 9? casing and then remove the larger BOP for a smaller 13? BOP during production. The current invention provides the solution of the need to swap BOPs by rather installing just the 13? BOP with the non-sealing casing shear rams 2,4.

[0032] In a preferred embodiment, the shear ram blade V angle 14 of the blades is 35 degrees. The V-angle 14 of the blade 10, 12 can vary from about 7? to 45 degrees. Additionally, in a preferred embodiment the back rake angle 16 of the blade 10,12 is 20 degrees with respect to a vertical line such as centerline 51 (see FIG. 2). It will be understood that vertical refers to the operational position of the BOP. However, the back rake angle 16 may vary from 7 to 25 degrees. The V angle 14 of the V shape blades will vary depending on the stroke length of the ram 2,4. Due to this, the non-sealing case shear ram 2,4 can use a 13? BOP to cut pipe 8 that is sized to with a casing diameter 24 (See FIGS. 5-6) at least 25 percent smaller than casing diameter 24 of the nominal bore 6 of the BOP opening.

[0033] In summary and reviewing back to FIGS. 1-8D, multiple views of a non-sealing casing shear ram assembly are shown in embodiments of the present invention. Those of skill generally recognize that pipes with an OD (outer diameter) 24 greater than 6? are considered to be casing whereas pipes with a smaller OD 24 may routinely be called drill pipe but could also be casing 8. The Ram geometry and blade geometry of both the upper and lower non-sealing shear rams 2, 4 are configured to cut 9? casing 8 when used with 13? 5K and/or 10K Blowout preventer. This feature is highly advantageous as prior art shear ram assemblies require a larger BOP to cut casing of that diameter, whereby the present invention alleviates the necessity of swapping the smaller 13? BOP for a larger 18? BOP for these operations.

[0034] Upper and lower non-sealing casing shear rams 2, 4 for use in a non-sealing case shear ram BOP may include an opening 6 through the BOP 100 (See FIG. 5). The casing 8 may be offset from the center of the bore 6. In FIGS. 7 and 8, upper and lower non-sealing casing shear rams 2, 4 each may include V-shaped ram cutter blades 10, 12. The V-shaped ram cutter blades 10, 12 may include a backwards rake angle 16 between 7? degrees and 45 degrees with respect to a diameter line through the opening or bore 6. In other embodiments, the upper and lower non-sealing casing may comprise a rake angle 16 between 7 degrees and 25 degrees with respect to a coaxial line through the opening or bore 6. The V-shaped ram shearing blades 10, 12 are configured to close and completely cut a pipe 8 in the opening 6 where an outer diameter 24 of the casing is at least 25% less than a diameter 26 of the bore 6. In other words, when the casing outer diameter is 25% less than the inner diameter of bore 6, e.g. utilizing a 13? inch BOP to cut 9? inch casing. For example 13??25% equals 3.4 inches. Subtracting this from 13 ? gives 13.625-3.4 or 10.225 inches. In other words, the rams are capable of cutting at least 9? casing. However, the rams may be capable of cutting casing 8 larger or smaller than 9? inches such as in the previous example. For instance, utilizing a 13? inch BOP 100 bore 8 with a 9? inch casing, the difference is approximately 30 percent relative the diameters 24, 26 of the casing 8 and the bore 6. Therefore, the rams 2, 4 being capable of shearing casing 8 that is at least 25 percent of the bore 6 means the rams 2, 4 are more than capable of shearing a 9? inch casing 8. This provides that in one possible embodiment the rams 2. 4 are configured to shear casing 8 with a diameter 24 at least in the range of 25-30 percent of the nominal bore diameter 26.

[0035] As another way of looking at it, 9? is 70.6% of 13?. Thus the present invention permits cutting casing with an outer diameter at least 70% of the inner diameter of the nominal borehole through the ram.

[0036] The upper and lower non-sealing casing shear rams 2,4 have a V-angle 14 which is between 30 and 40 degrees and the back rake angle 16 is between 15 degrees and 35 degrees. In one embodiment, the V-shape angle 14 is between 33 and 38 degrees and the back rake angle 16 is between 15 degrees and 25 degrees. In one preferred embodiment, the angle of the V-shape 14 is 35 degrees, and the back rake angle 16 is approximately 20 degrees. The angle of the V-shape 16 is identical for the upper and lower non-seal casing shear rams 2,4. The rake angle 16 is the same for the upper and lower non-seal casing shear rams 2,4. The V-shaped upper ram cutter blade 10 for the upper casing shear ram 2 is a mirror image of the V-shaped lower ram cutter blade 12 for the lower casing shear ram 4.

[0037] The V-shaped cutting blades 10, 12 on the upper and lower non-sealing casing shear rams 2, 4 cover the entire diameter 26 of the nominal bore 6 as shown in FIG. 3. As the shear rams 2, 4 move from an open position with respect to the nominal bore 6 as depicted in FIG. 2, to a closed position with respect to the nominal bore 6 as shown in FIG. 1, the upper and lower blades 10, 12 shear the casing 8. Additionally, as the upper and lower non-sealing shear rams 2, 4 move towards the closed position, as shown in FIG. 4, they engage the casing 8 from the periphery and guide the casing 8 towards the center of the bore 6 for a complete shear as shown in FIGS. 5 and 6. To accommodate the required sized ram blades 10, 12 to cover the entire bore diameter 26 within the smaller BOP size as described herein, the Shear ram assembly 100 is non-sealing as allowed under API-16A 4.sup.th Edition which is promulgated by the American Petroleum Institute.

[0038] The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description only. It is not intended to be exhaustive or to limit the invention to the precise form disclosed; and obviously many modifications and variations are possible in light of the above teaching. Such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims.