Patent Application
20060038147
1. Field of the Invention
This invention relates to a unitary, i.e., one piece, blade seal for use in a shearing blind ram for a ram-type blowout preventer used in oil and gas drilling 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. Replaceable sealing elements called packers are mounted on the ends of the pistons which extend into the blowout preventer bore. When these pistons are moved to a closed position, commonly referred to as “closing the blowout preventer” or “closing the rams”, the vertical bore of the blowout preventer is sealed and the kick is contained. These packers are available in a variety of configurations designed to seal the blowout preventer bore when the opposing pistons are moved to their closed position. One type of packer has ends designed to seal around pipe of a specific size in the blowout preventer bore when the blowout preventer is closed. Other rams are designed to shear through a drill pipe section extending through the vertical bore and seal off the bore. It is this type, commonly referred to as blind shear rams and the blade seal to be used therein to which the present invention is directed.
These shearing blind rams face a formidable task. They must be able to shear through a piece of drill pipe in the blowout preventer bore and then seal against each other to contain the well bore pressure during a kick. The shearing blind rams must form a pressure tight seal during a kick until the well bore pressure can be controlled which can reach several thousand pounds per square inch. The shearing blind ram has various rubber seal elements attached to it to ensure a complete seal of the blowout preventer bore.
These seal elements, including the blade seal of the present invention, are exposed to tremendous well bore pressures. The blade seal of the current invention offers a substantial improvement by offering a simple, easy to manufacture blade seal that minimizes wear and tear of the elastomeric seal element with a pair of end caps to minimize extrusion of the seal element.
2. Description of Related Art
Various types of shearing blind rams with various blade seals have been shown and used.
U.S. Pat. No. 3,766,979 to J. T. Petrick shows a well casing cutter uitilizing O rings to seal around the casing being cut.
The ram-type blowout preventer shown in U.S. Pat. No. 3,817,326 to M. J. Meynier III discloses a blade seal with the rubber element bonded to a metal member.
U.S. Pat. No. 4,081,027 to T. X. T. Nguyen. shows a shearing ram for hydrogen sulfide service utilizing a rubber element bonded to the shear ram to seal after shearing.
The wellhead shearing apparatus shown in U.S. Pat. No. 4,341,264 to F. H. Cox et al. discloses a rubber element bonded in a recessed groove in a shearing ram to act as a blade seal.
U.S. Pat. No. 4,347,898 to M. R. Jones shows a shear ram blowout preventer utilizing a rectangular seal in the lower face of the upper ram as a blade seal.
A shearing ram utilizing a pair of hardened points to aid in initiating the shearing action is shown in U.S. Pat. No. 4,537,250 to J. N. Troxell, Jr. A plain rectangular seal acts as a blade seal.
The shear ram apparatus shown in U.S. Pat. No. 4,540,046 to S. W. Granger et al. discloses a blade seal with the rubber element bonded to a metal member.
U.S. Pat. No. 5,005,802 to D. J. McWhorter et al. shows a variable bore packer for a ram type blowout preventer.
U.S. Pat. No. 5,360,061 to L. M. Womble shows a blowout preventer with tubing shear rams designed to control the shape of the sheared pipe end.
The shear ram apparatus shown in U.S. Pat. No. 5,515,916 to T. D. Haley discloses a blade seal with the rubber element bonded to a metal member and a metal insert in the rubber element to aid in sealing.
U.S. Pat. No. 5,713,581 to D. W. Carlson et al. shows a blade seal of nitrile rubber with uniformly dispersed synthetic, non-cellulosic fibers to aid in preventing seal rollover.
U.S. Pat. No. 6,158,505 to R. Araujo shows a blade seal design utilizing a pair of tapered blade seal elements to effectuate sealing.
The blade seal for a shearing blind ram of the present invention is designed for use in a standard ram-type blowout preventer used in oil and gas drilling 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 blade seal includes an elongate member having a generally semi-circular cross section with a curved upper surface and a substantially flat lower surface. The flat lower surface has a pair of laterally extending sides that taper outwardly and have a metal outer cap bonded thereto. The metal outer caps form an acute angle that engages a complementary groove formed in the upper ram of the shearing blind ram assembly. The opposing lower ram has a upwardly facing surface that seals against the blade seal after the pipe is sheared.
A principal object of the present invention is to provide a unitary blade seal for use in shearing blind rams that has an improved life cycle and fits in existing blowout preventers.
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.
These and other objects and advantages of the present invention are set forth below and further made clear by reference to the drawings, wherein:
With reference to the drawings, and particularly to
Shearing blind ram assembly 28 is shown in an exploded view in
Referring to
As best seen in
A typical sequence of operation is as follows. With shearing blind ram assembly 28 installed in blowout preventer 10, the rams are closed. This causes pipe 64 to be sheared and lower face 50 of upper ram 34 and seal surface 42 of lower ram 32 to slide over one another in close fitting relationship. Continued movement causes seal surface 42 of lower ram 32 to contact and seal against curved upper surface 56 of blade seal 30 as best seen in
The construction of my unitary blade seal for a shearing blind ram will be readily understood from the foregoing description and it will be seen that I have provided a unitary blade seal that has an improved life cycle and fits in existing blowout preventers. Furthermore, while the invention has been shown and described with respect to certain preferred embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the appended claims
