WO2015139015A1

WO2015139015A1 - Coiled Tubing Extended Reach with Downhole Motors

Info

Publication number: WO2015139015A1
Application number: PCT/US2015/020653
Authority: WO
Inventors: Oyedokun OLUWAFEMI; Jerome SCHUBERT
Original assignee: The Texas A&M University System
Priority date: 2014-03-14
Filing date: 2015-03-16
Publication date: 2015-09-17
Also published as: US20170009529A1

Abstract

Disclosed is a method to enhance the reach of coiled tubing in the lateral section of a wellbore. The application of this method may enhance the use of coiled tubing in drilling very deep flowing wells. Similarly, the method may be applied in increasing the reach of the tubing for other coiled tubing well intervention applications. The method involves the use of downhole motor assemblies, stabilizers, and dynamic torque arrestors to rotate coiled-tubing string.

Description

Coiled Tubing Extended Reach with Downhole Motors

BACKGROUND OF THE INVENTION

Field of the invention

The fieki of the disclosure is directed to coiled tubing drilling applications, and more specifically extending the reach of coiled tube piping in lateral sections of the welibore.

Backgroun of the In yentiop

Currently,, the coiled tubing industry needs a technology that may enhance the reach of the tubing in the lateral section of the -welibore. The inability to rotate the tubing limits its reach in the lateral section of the welibore. Past and current extended-reach techniques for coiled tubing have not been sufficient, individually, in increasing significantly the reach of the tubing in the welibore. Often, four or live extended-reach, methods are combined to have significant reach in the welibore, which is quite expensive to do.

Consequently, there is a need for a single inexpensive method to extend the reach of coiled tubing in lateral welibores. With the drive of exploiting oil and gas resources from deep wells increasing today, the reach of coiled tubing in the welibore needs to be increased to meet this growing demand. The application of this technique ma enhance the use of coiled tubing i drilling very deep flowing wells. Similarly, the method may be applied for increasing the reach of the tubing for other eoiled-tubing well intervention applications.

BRIEF SUMMARY OF SOME OF THE PREFERRED EMBODIMENTS

These and other needs in the art are addressed in one embodiment by a method of drilling laterally with coiled tubing, wherein, the method involves attaching a drill assembly to a coiled tubing, and attaching a second motor assembly to the drill assembly. The method also includes inserting the second motor assembly, the drill assembly, and the coiled tubing downhole, and attaching a first motor assembly to the coded tubing. The method further includes inserting the first motor assembly downhole, rotating the coiled tubing with the first motor assembly, and rotating the drill assembly with the second motor assembly.

Further embodiments are addressed by a dynamic torque arrestor comprising a casing, an. adaptor, and connector, wherein the casing houses an inner casing, a spindle, a machined spring, an upper plate, and a lower plate.

The foregoing has outlined rather broadly the features and technical advantages of the present disclosure so that the detailed description that .follows may be better understood. Addi tional features and advantages of the disclosure will be described hereinafter that form the subject of the claims. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilised as a basis for modifying or designing other embodiments tor carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent embodiments do not depart from the spirit and scope of the disclosure as set forth in the appended claims.

BRIEF DESCRIPTION ^'OF THE DRAWINGS

For a detailed description of the preferred embodiments of the disclosure, reference will now be made to the accompanying drawings in which:

Figure 1 illustrates a cut away view of the coiled tubing downhoie assembly;

Figure 2 illustrates an embodiment of a stabilizer;

Figure 3 illustrates an embodiment of a dynamic torque arrester;

Figure 4 illustrates an embodiment of a drill assembly;

Figure 5 illustrates an embodiment of a second motor assembly with stabilizers; and Figure 6 illustrates an embodiment of downhoie electric motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Disclosed, embodiments of a downhoie assembly may extend the lateral reach of coiled tubing. Embodiments may include systems and methods of operation to extend the reach of coiled tubing laterally. These systems and methods may be used in drilling extended reach wells and/or used for worfcovers in extended reach wells.

n embodiment, as illustrated in Figure 1 , a downhoie assembly 5 may comprise coiled tubing 10, a first motor assembly 15, a dynamic torque arrester 20, a stabilizer 25, a second motor assembly 30, and a drill assembly 35. Downhoie assembly 5 may be employed to extend the reach of coiled tubing 10 in downhoie operations, more specifically lateral drilling operations. Coiled tubing 10 may comprise of a single tube that may be spun around a reel, not illustrated, and straightened before entering a well. During operations, a single coiled, tube 10 may be used or a pluralit of coiled tubing 10 may be used in conjunction with each other. Coiled tubing 10 may be an diameter suitable for drilling operations, A suitable diameter may be between, about half an inch. to_. about five inches, about an inch to about three inches, about two inches to about four niches, or about three inches to about five inches. To withstand a downhoie environment, coiled tubing 10 may be any suitable material. Suitable material: may be stainless steel, steel, carbon fiber, iron, black iron, or an combination thereof. As illustrated in Figure K coiled tubing 10 may be disposed downhoie and connect to stabilizer 25 and first motor assembly 15, in embodiments, additional coiled tubing 50 may be used to connect first motor assembly 15 to second motor assembly 30 and drill assembly 35. During operations, first motor assembly 15 and second motor assembly 30 may create rotational forces. Rotational .forces created by fist, motor assembly 15 may prevent coiled tubing 1.0 from rubbing against a rock formation. Additionally, preventing coiled tubing 10 from twisting and rotating into a rock formation, stabilizers 25 may be disposed along coiled tubing 10, first motor assembly 15, and/or second motor assembly 30,

Stabilizer 25 may prevent coiled tubing 10 from touching the subterranean formation downhole. Additionally, stabilizers 25 may also prevent twisting and rotation of downhole assembly 5, In embodiments, as illustrated in Figure 2, stabilizer 25 may comprise a. base 28 and/or a blade .26. Blade 26 may further comprise an elastomeric pads 27. Stabilizer 25 may ha ve any number of blades 26 with any number of elastomeric pads 27. Elastomeric pads 21 may be disposed on the outside of blades 26, Blades 26 and elastomeric pads 27 ma press against a subterranean rock: formation_* preventing torque. Blades 26 may also push coiled tubing 1 away from the subterranean: formation rocky surface downhole. In embodiments- there may be a plurality of stabilizers 25 used during downhole operations. Stabilizers 25 may be connected in series and or be separated by additional downhole devices, in embodiments, the number of Stabilizers 25, and their spacing, may be based on the diameter of coiled tubing 10. A smaller diameter may require larger amounts of stabilizers 25 that are spaced closer together. This may prevent coiled tubing !O from contacting the rock surface of a subterranean formation. A large diameter may require less stabilizers 25 that are spaced farther apart. Referring to Figure 5. a stabilizer 25 may be positioned below a first motor assembly 15, and a plurality of stabilizer 25 may be positioned above first motor assembly 15. In an embodiment, not illustrated, there may be a plurality of stabilizers 25 below fist motor assembly 15 and a plurality of stabilizers 25 above first, motor assembly 15. Stabilizer 25 may connect directly or indirectly with first motor assembly 1 . First motor assembly 15 and stabilizer 25 may be connected by any suitable means. Suitable means may be, but are not limited to, a press fitting, nuts and bolts, threaded connector, or any combination thereof

As illustrated in Figure 2, a plurality of stabilizers 25 may be connected by coiled pipe 10. Coiled pipe 10 may rotate freely between stabilizers 25. To prevent slipping and/or keep coiled pipe 10 centered downhole, stabilizer 25 ma be made of any suitable material. Suitable material may be steel, stainless steel, black, iron, plastic, or any combination thereof, in embodiments, base 28 may be any suitable length to prevent stabilizer 25 from slipping. A suitable length may be about one foot to about six feet, about two feet to abou four feet, about three feet to about six feet, or about: one foot to about three feet. Blades 26 may traverse base 28 any suitable length to preven stabilizer 25 from slipping, in embodiments, stabilizers 25 may be disposed about second motor assembly 30 and drill assembly 35. Additionally, stabilizers 25 may be disposed about other dowrihole devices.

As illustrated, in Figure I , stabilizers 25 may be disposed about and/or connect to a dynamic torque arrester 20. in embodiments,, there may be a plurality of dynamic torque arresters 20 used so d wnbok Operations. Dynamic torque arrestor 20 may connect directly or indirectly with first motor assembly 15 and/or second motor assembly 30 by any suitable means. Suitable means may be, but are not limited to, a press fitting, nuts and bolts, threaded connector, or any combination thereof. Dynamic torque arrestor 20 may prevent torque produced by first motor assembl 15 and/or second motor assembly 30 from twisting, moving, and/or breaking dowtibo!e assembly 5 withi the we.ilbo.re. As illustrated in Figure 3, dynamic torque arrestor 20 may comprise a casing 40, an adapter 4 L a lower plate 42, an eiastomerie pad 43, a machined spring 44, an inner casing 45, an. axial roller bearing 46, a thrust bail bearing 47, a spindle 48, a high viscous fluid 49, an upper plate 50, perforations 51, and connector 60. Casing 40 may act as an outer shell thai protects internal parts from the downhole environment which ma include, but is not limited to, mud, rock, water, and other subterranean elements. Casing 40 may comprise any suitable material. Suitable material ma include, but is not limited to, carbon steel, stainless steel, plastic, or any combination thereof. Located at one end of dynamic torque arrestor 20, adapter 41 , may attach coiled tubing 10, first motor assembly 15, second motor assembly 30, and or stabilizer 25 to dynamic torque arrestor 20. Adapter 41 may attach to any downhok device by any suitable means. Suitable means may be, but are not limited to, a press fitting, nuts and bolts, threaded connector, and/or any combination thereof. In embodiments, adapter 41 may rotate about its axis which may help dissipate lateral movement that may he produced by first motor assembly 15 and/or second motor assembly 30,

Disposed inside casing 40, above adapter 41 , is lower plate 42. Lower plate 42 ma act to hold machined spring 44 in place. There may be any number of lower p lates 42 that may hold and guide machined spring 44. Lower plate 42 may be secured to casing 40 by any suitable means which may include, but is not limited to, an form of welding, nuts and bolts, press fitting, and/or any combination thereof.

Eiastomerie pad 43 may be attached to lower plate 42 along the inner most edge adjacent to machined spring 44. Eiastomerie pad 43 may be attached by any suitable means which may include, but is not limited to, adhesive, press fitting, screws, and/or any combination thereof. Eiastomerie pad 43 ma comprise any suitable material that may act as a buffer to prevent wear and tear between machined spring 44 and lower plate 4.2, Suitable material may be, but is not limited to, any form of plastic, leather, neoprene, rubber, and/or an combi nation thereof.

Machined spring 44 ma be disposed upon adapter 41 and may be held in place by lower plate 42 and eiastoroeric pad 43, Machined Spring 44 may comprise any suitable material. Suitable material may include, but is not limited to, carbon steel, stainless steel, plastic, or any combination thereof. Machined spring 44 may be of any resistance and length necessary to withstand torsional and axial loads that may be produced and transmitted through adapter 41 by first motor assembly 15 and/or second motor assembly 30, Machined spring 44 may move vertically within casing 40 to help dissipate torsional and axial loads. Spindle 48 may be placed upon machine spring 44 to prevent machined spring 44 from moving the entire vertical length of casing 40.

Spindle 48 may be of any suitable length to prevent machine spring 44 from moving the entire vertical length of casing 40. A suitable length ma be about two inches to about twelve inches, about four inches to about ten inches, about six inches to about eight inches, or about six. inches to about twelve inches. Spindle 48 may be of any suitable material which may be, but is not limited to, stainless steel, plastic, carbon steel, and/or any combination thereof. Spindle 48 may be of any suitable diameter to withstand forces placed upon it by machined spring 44. A suitable diameter may be about half a centimeter to about ten centimeters, about two centimeter to about eight centimeters, about four centimeters to about six centimeters, or about five centimeters to about ten centimeters. Spindle 48 may rest upon machined spring 44 at. one end and at the opposite end be disposed in inner casing 45,

Inner casing 45 may be of any suitable material, which may be, but is not limited to, stainless steel, plastic, carbon steel, and/or any combination thereof. Inner easing 45 may comprise highly viscous fluid 49, thrust ball bearing 47, and axial roller bearing 46. Inner casing 45 may have a .flanged end in which to attach to upper plate 50. inner casing 45 may be attached to upper plate 50 by any suitable means which may use, but. is not limited to, nuts and bolts, adhesives, any form of weld, press fitting, and/or any combination thereof. Opposite the flanged end of inner casing 45 may be a capped end with a point of entry 52 for spindle 48 to pass through. Within inner casing 45, high viscous fluid 49 ma comprise, but is not limited to, glycerine, heavy motor oils, axial grease, marine grease, magneto-rheological fluids, eleetro-rheologica! fluids, and/or any combination thereof. High viscous fluid 49 may provide resistance to prevent the rapid and or upward movement of spindle 48. Spindle 48 ma move as machined spring 44 reacts to torsional and axial loads produced by adapter 4.1. High viscous fluid 49 may furthe help dissipate torsional and axial loads experienced by spindle 48, preventing torsional and axial loads from transferring to dynamic torque attestor 20. Point of entry 52 may he of any suitable diameter that may accommodate spindle 48. A suitable diameter may be about half a ^'centimeter to about ten centimeters, about two centimeter to about eight centimeters, about four centimeters to about six centimeters, or about five centimeters to about ten centimeters. Point of entry 52 may comprise any form of buffer material to prevent wear and tear on spindle 48, Butter material may be, but is not limited to, any form of plastic, leather, neoprene, rubber, and/or any combination thereof. Point of entry- S may also guide spindle 48 and prevent any lateral movement.

Axial toller bearing 46 may also guide spindle 48 and prevent any lateral movement. Axial roller bearing 46 may comprise any number of roller bearings within a housing. Roller bearings may be of any radius .suitable to prevent laieral movement of spindle 48. Roller bearings may be any suitable materia! which includes, but is not limited to, carbon steel stainless steel, plastic_* or any combination thereof Any form of lubricant may be used to allo for roller bearings to move freely in axial roller bearing housing 60. Lubricant may be, but is not limited to, axial grease or marine grease. Axial roller bearing 46 may attach within inner casing 45 above point of entry 52. Axial roller bearing 46 may be attached by any suitable means which, may include, but is not limited to, any form of welding, nuts and bolts, or press fitting.

Thrust ball bearing 47 may also guide spin^'dle 48 and prevent any lateral movement. Thrust bai l bearing 47 may comprise an number of roller bearings wi thin a housing. Thrust ball bearing 47 may be of any radius suitable to prevent lateral movement of spindle 48.

Thrust ball bearing 47 may be any suitable material which includes, but is not limited to, carbon steel, stainless steel, plastic, and/or any combination thereof. Any form of lubricant may be used to allow for thrust ball bearing 47 to move freely in axial roller bearing housing 60. Lubricant, may be, but i not limited to. axial grease, marine grease, and/or any combination thereof. Thrust ball bearing 47 may attach within inner casing 45 above point of entry 52 and axial roller bearing 46. Thrust ball bearing 46 may be attached by any suitable means which may include, but is not limited to, any form of welding, nuts and bolts, press fitting, and/or any combination thereof.

Inner casing 45 may be separated into two distinct areas by separator 53. Separator 53 may comprise any suitable material. Suitable material may include, but is not limited to, carbon steel, stainless steel, plastic, and/or any combination thereof. The lower separated area 65 may house thrust, bail bearing 47 and axial -roller bearing 46. The upper separated area 70 may house highly viscous fluid 49. Highly viscous fluid 49 may act to prevent the rapid lateral movement of spindle 48, Spindle 48 enter the upper separated area 70 through a second poin t of entry 54, Second point of entry 54 may be of any suitable diameter that may accommodate spindle 48. A suitable diameter may be about half a cemimeter to about ten centimeters, about two centimeter to about eight ceniimeters, about four ceniimeters to about six centimeters,, or about five centimeters to about ten centimeters. Second point of entry 54 may comprise any form of buffer material to prevent wear and tear on spindle 48. Buffer material may be, but is not limited to, any form of plastic, leather, neoprene, rubber, and/or any combination thereof. Buffer materia! may create an air tight seal to prevent highl viscous fluid 49 from moving into the lower separated area 65 which may house thrust bail bearing 47 and axial roller bearing 46. Second point of entry 54 may also guide spindle 48 and prevent any lateral movement.

As discussed above, upper plate 50 may be used for attaching inner casing 45 to dynamic torque arrester 20. Upper plate 50 may be located inside casing 40 at the opposite end of adapter 41. Upper plate 42 may act to hold inner easing 45 in place. Upper plate 50 may comprise any suitable material. Suitable material may include, but is not limited to, carbon steel, stainless steel, plastic, and or any combination thereof. Upper plate 50 may have perforations 51 which may allow .for drilling mud to pass through. There may be a plurality of perforations 51 , which, may be of any diameter suitable to allow f r mud to flow freely through. A suitable diameter may be about half a centimeter to about ten ceniimeters, about two centimeter to about eight centimeters, about four centimeters to about six centimeters, or about fi ve centimeters to about ten centimeters.

Opposite adapter 41 is connector 60 which may be used to attach to dynamic torque arrester 20, coiled, tubing 10, first motor assembly 15, second motor assembly 30, and/or stabilizer 25. Connector 60 may attach to any device by any suitable means. Suitable means may be, but are not limited to, press fitting, nuts and bolts, and/or threaded connector. Stabilizer 25 and/or dynamic torque arrestor 20 may be used prevent the rotational movement, produced by first motor assembly 15, from moving up coiled tubing 10, A first motor assembly 15 may comprise mud motor 200, electric motor 100. and/or turbine motors, As illustrated in Figure 6, first motor assembly 15 may comprise electric motor 100 and/or a mud. motor 200. Electric motor 100 may be used in conjunction with mud motor 200 or as a standalone first motor assembly 15. Electric motor 100 ma comprise a rotor shaft 101, bearings 1.02, annulus gear 103. and planet carrier 104. Electric motor 100 may connect to coiled tubing 10, stabilizers 25, dynamic torque arrestors 20, and/or mud motor 200 by any suitable means. First motor assembly 15 may be used to turn coiled tubing 10, which may further be attached to a second motor assembly 30 and/or a drill assembly 35,

In embodiments, as illustrated in Figure 4, drill assembly 35 may comprise a drill bit 36, connector 37, and/or directional drilling assembly 38. In embodiments, drill assembly 35 may attach to a second motor assembly 30. Drill assembly 35 may connect to second rooior assembly 30 by any suitable means. Suitabl means may be, but are not limited to, press fitting, nuts and. bolts, threaded connector, and/or any combination thereof, Second motor assembly 30 may be used to help turn drill assembly 35, In embodiments second motor assembly 30 ma ^'be an electric motor 100, mud motor 200, and/or a turbine motor.

Drilling bit 36 may be of any type suitable to drill through a subterranean formation. Drill bit 36 may attached to connector 37 by any suitable means. Connector 37 is attached to directional drilling assembly 38, opposite drill bit 36, by any suitable means. Second motor assembly 30 may attach to directional drilling assembl 38, opposite connector 37, by any suitable means. Second motor assembly 30 may connect drilling assembly 35 to coiled tubing 10. Second motor assembly 30 may connect to coiled tubing 10 by any suitable means. First motor assembly 15 may attach to coiled tubing 10 at any suitable length from second motor assembl 30. As illustrated in Figure 5, first motor assembly 15 may attach to coiled tubing 10 by any suitable means. Suitable means may be, but are not limited to, clamps, bolts, nuts and bolts, threads, and/or any combination thereof. In embodiments, first motor assembly 15 and second motor assembly 30 may be disposed between different sections of coiled tubing 10. Second motor assembly 15 may be attached to a stabilizer 25 and/or dynamic torque arrestor 20 by any suitable means. There may be any number of stabilisers 25 and/or dynamic torque arresters 20 attached to second motor assembly 15. Depending on the specific application, there may only be a single or multiple stabilizer 25 with a single or multiple dynamic torque arresters 20. Stabilisers 25 and dynamic torque arresiors 20 may be attached below or above second first motor assembly 15, Furthermore, both stabilizer 25 and dynamic torque arrestor 20 may be used together or in any order.

During downhole operations, a method may be used to properly employ downhole assembly 5. The method may comprise drilling vertically with coiled tubing 10 and drill assembly 35 to a designated depth, At the designated depth, drill assembly 35 may then be controlled to move laterally across a formation. After drilling laterally to the extent allowed by coiled tubing 1.0, drill assembl 35 and coiled tubing 10 may be brought back to the surface. At the surface, coiled tubing 10 is altered to extend the lateral drilling reach of downhole assembly 5. Coded tubing it⁾ may be fitted with drill assembly 35, a second motor assembly 30, a first moto assembly 15, dynamic torque arrestor 20, and stabilizer 25. Once fitted, downhole assembly 5 is placed downhole to where drilling operations stopped.

During operations, first motor assembly 15 may rotate coiled tubing 10, preventing coiled tubing 10 from dragging along the lower most horizontal surface of the lateral drilled hole 60 and downhole bend 70, as illustrated in Figure I . Generally, most lateral drilling is limited in depth due to the amount of pipe that ma be in contact with the surface wall of lateral drilled hole 60. Currently, as drill assembl 35 moves laterally, coiled tubing 10 drags along lateral drilled hole 60, This creates large amounts of friction along coiled pipe 10, the friction generated may eventually prevent the lateral movement of drill assembl 35. As disclosed, to overcome the friction, a First motor assembly 15 rotates the coiled tubing 10 section between first motor assembly 15 and second motor assembly 30, Rotation of the coiled pipe 1 by first motor assembly 15 may prevent coiled tubing 10 from dragging along lateral drilled hole 60. Rotation of the pipe prevents friction from being generated along coiled tubing 1.0. The reduction in friction may allow for drilling to move further lateral. Second motor assembly 30 may be used to drive drill, assembly 35 through the formation laterally. Using the second motor assembly 30 to drill and the first motor assembl 15 to rotate the coiled tubing 10 may allow dowiihole drilling operations to move laterally across the formation. Coiled tubing 10 may also be prevent from dragging along the surface of drilled hole 60 and downhole bend 70, Moreover, the reachable drilling lengt of coiled tubing 1 in downhole operations may be increased.

Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the disclosure.

Claims

What s claimed is:

t . A method of drilling with coiled tubing, the method comprising;

attaching a drill assembly to a coiled tubing;

attaching a second motor assembly to the drill assembly;

inserting the second motor assembly, the drill assembly, and the coiled tubing downhole;

attaching a first motor assembly to the coiled tubing:

inserting the first motor assembly do nhole;

rotating the coiled tubing with the first motor assembly; and

rotating the drill assembly with the second niotor assembly.

2. The method of claim 1 , wherein the first motor assembly rotates the coiled tubing between the first motor assembl and the second motor assembly.

3. The method of claim 1 , wherein the drill assembly further comprises a drill bit,

4. The method of claim 1 , wherei the first motor assembly is connected to a stabilizer,

5. The method of claim 4, further wherein there are at least two stabilizers.

6. The method of claim 1, wherein the first motor assembly is connected to a dynamic torque, arrester.

7. The method of claim 6, further wherein there are at least two dynamic torque arresters.

8. The method of claim 1, wherein the motor assembly is connected to both a stabilizer and a dynamic torque arrester.

9. The method of claim 8, wherein the first motor assembly is connected to a plurality of stabilizers and a plurality of dynamic torque attestors,

10. A dynamic torque arrester, comprising:

a casing;

an adapter at one end of the casi ng; and

a connector opposite the adapter.

1 1. The dynamic torque arrestor of claim 10, wherein the easing further comprises:

an inner casing;

a spindle;

a machined spring;

an upper plate; and

a lower plate.

12. The dynamic torque arrestor of claim 1 1, wherein the inner casing is attached to the upper plate.

13. The dynamic torque arrestor of claim 11, wherein the inner casing is divided into a Sower and an upper area,

14. The dynamic torque arrestor of claim 13, wherein the lower area further comprises;

a thrust bail bearing: and

an axial roller bearing.

15. The dynamic torque arrestor of claim 13, wherein the upper area further comprises highl viscous fluid.

16. The dynami tor ue arrestor of claim 1 1 , wherein the machined spring is disposed upon the adapter.

17. The dynamic torque arrestor of claim 1 1 , wherein the lower plate guides and prevents lateral movement of the machined spring.

18. The dynamic torque arrestor of claim 17 , further comprising multiple lower plates.

1 . The dynamic torque arrestor of claim 1 1 , wherein the spindle is disposed upon the machined spring,

20. The dynamic torque arrestor of claim 1 1 , wherein the upper plate further comprises perforations.

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