Wells – Means for perforating – weakening – bending or separating pipe...
Reexamination Certificate
2000-03-07
2001-06-12
Tsay, Frank (Department: 3672)
Wells
Means for perforating, weakening, bending or separating pipe...
C166S085400
Reexamination Certificate
active
06244336
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved shear ram cutting blade configuration for use in a shearing ram for a ram-type blowout preventer used in oil and gas drilling and workover operations. Ram-type blowout preventers are part of a pressure control system used in oil and gas drilling operations to control unexpected well bore pressure spikes or “kicks” as they are commonly referred to in the industry.
The blowout preventer has a body with a vertical bore and a pair of laterally disposed opposing bonnet assemblies. Each bonnet assembly includes a piston which is laterally moveable within the bonnet assembly by pressurized hydraulic fluid. The opposite end of the pistons each have a connecting rod attached thereto which in turn has a shear ram mounted thereon. These shear rams are designed to shear or cut through any member, such as tubing or seismic logging cable, disposed within the blowout preventer body's vertical bore. This sudden closing of the rams is necessary when a well bore pressure spike or kick is detected during downhole operations such as well logging or well maintenance. Due to the need to rapidly seal the well bore, there is insufficient time to retrieve the aforementioned tubing or cable from the well bore before closing the rams. Therefore it is necessary to have shear rams that can cleanly cut through these members and seal the well bore.
These shear rams face a difficult task. Recent requirements promulgated by some drilling contractors include the ability of the shear rams to shear up to ten strands of cable, multiple strings of steel tubing or a combination of the two, or multiple strings of a composite tubing with electrically conducting wires in the wall. Each of these requirements poses similar yet different requirements on the shear rams. In the case of multiple strands of cable the flexibility of the cable along with its inherent toughness makes it particularly difficult to shear or cut cleanly without leaving partially cut strands of the cable in the blowout preventer bore and thereby making it especially difficult for the shear rams to seal after the cutting or shearing operation. Shearing multiple strings of tubing poses an almost opposite problem in that their rigid structure causes the individual strings of tubing to flatten and extend beyond the outer edges of the shear ram cutter blades as they are initially squeezed by the blades. This can cause unsheared pieces of tubing to interfere with the closing operation of the shear rams and difficulties in sealing.
Thus, the shear rams in a ram-type blowout preventer must be able to cleanly shear a variety of members and seal the blowout preventer bore afterward in daily operation. The double shearing rams of the current invention offer a significant improvement over existing shear ram designs without requiring any changes to the existing blowout preventer design.
2. Description of Related Art
U.S. Pat. No. 5,501,424 to M. R. Williams et al. gate valve adapted for cutting wireline using an insert in the gate and seat for shearing a wireline cable disposed therein.
The shearing gate valve apparatus shown in U.S. Pat. No. 5,803,431 to L. G. Hoang et al. discloses a gate with a layer of hard facing material welded to the face of the gate to ensure the gate does not form an upset during shearing operations that would interfere with sealing operations.
SUMMARY OF THE INVENTION
The double shearing rams of the present invention are designed for use in a standard ram-type blowout preventer used in oil and gas drilling and workover operations. The blowout preventer has a body with an axial bore, a pair of opposing bonnet assemblies and a pair of opposing rams laterally moveable within the bonnet assemblies by a pressurized fluid source to control flow of well fluids through the blowout preventer body axial bore. The double shearing rams includes an upper shear ram operated by one bonnet assembly and an opposing lower shear ram operated by the other bonnet assembly. The lower shear ram is generally shaped like a rectangular parallelepiped with a pair of opposite sides rounded to fit the blowout preventer body. The lower shear ram includes a cutting blade on one side with a notched cutting edge formed on its leading edge.
The upper shear ram also is generally shaped like a rectangular parallelepiped with a pair of opposite sides rounded to fit the blowout preventer body. The upper shear ram includes an upper cutting blade and a lower guide blade vertically spaced to form a cavity therebetween. The cavity is sized to receive the lower ram's cutting blade in close fitting engagement when the rams are closed. The upper shear ram has a primary cutting edge formed on its leading edge and a secondary edge vertically and axially displaced from the primary cutting edge. During shearing operations, initial movement of the shear rams allows the upper shear ram's primary cutting edge to cooperate with the lower shear ram's cutting blade to make an initial shear of the member or members in the blowout preventer's bore. Further closing of the shear rams allows the upper shear ram's secondary cutting edge to cooperate with the lower shear ram's cutting blade to make a second shear of any remaining member or members in the blowout preventer's bore. A plurality of guide pins positioned on the upper shear ram and the cutting blade of the lower shear ram cooperate to maintain the members to be sheared between the upper and lower shear ram.
A principal object of the present invention is to provide improved shear rams for use in a ram-type blowout preventer that facilitates the clean and complete shearing of multiple cables in the blowout preventer bore with a double shearing configuration.
Another object of the present invention is to provide improved shear rams for use in a ram-type blowout preventer that facilitates the clean and complete shearing of multiple steel tubing strings in the blowout preventer bore with a retention mechanism to ensure the tubing strings stay between the shear rams until the shearing is complete.
These with other objects and advantages of the present invention are pointed out with specificness in the claims annexed hereto and form a part of this disclosure. A full and complete understanding of the invention may be had by reference to the accompanying drawings and description of the preferred embodiments.
REFERENCES:
patent: 3561526 (1971-02-01), Williams, Jr. et al.
patent: 3817326 (1974-06-01), Meynier, III
patent: 4081027 (1978-03-01), Nguyen
patent: 4132266 (1979-01-01), Randall
patent: 4132267 (1979-01-01), Jones
patent: 4215749 (1980-08-01), Dare et al.
patent: 4240503 (1980-12-01), Holt, Jr. et al.
patent: 4313496 (1982-02-01), Childs et al.
patent: 4347898 (1982-09-01), Jones
patent: 4508313 (1985-04-01), Jones
patent: 4580626 (1986-04-01), Jones
patent: 4646825 (1987-03-01), Van Winkle
patent: 5360061 (1994-11-01), Womble
patent: 5501424 (1996-03-01), Williams et al.
patent: 5515916 (1996-05-01), Haley
patent: 5803431 (1998-09-01), Hoang et al.
Cooper Cameron Corp., BOP Replacement Parts Catalog, Jul. 1998, p. 41, “T BOP Shearing Blind Rams”.
Cooper Cameron Corporation
Jackie Lee Duke
Tsay Frank
LandOfFree
Double shearing rams for ram type blowout preventer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Double shearing rams for ram type blowout preventer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Double shearing rams for ram type blowout preventer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2506669