Varco Shaffer, Inc.

David L O'Donnell

Melvyn F Whitby

Tri Canh Le

Frank L Sklenka

A hydraulically controlled ram actuating mechanism 10 for a blowout preventer controls the opening and closing of a ram block 12 interconnected with a ram 14 movable within a ram housing 26 along ram axis 16. The ram piston 24 and a locking piston 62 are each movable within the ram housing in response to fluid pressure. The locking piston includes a plurality of substantially planar tapered locking piston surfaces 72 circumferentially arranged on the exterior of the locking piston and inclined at an acute positive cam angle. A plurality of locking rods 40 are each secured to the ram housing 26 and are circumferentially spaced about the locking piston, with each locking rod including a substantially planar tapered locking rod surface 82 thereon inclined at an acute negative cam angle. A plurality of locking segments 60 are each spaced radially between a locking rod and the locking piston, with each locking segment adapted for being sandwiched between the locking surfaces for preventing opening of the ram until the locking piston is moved in response to fluid pressure. The actuating mechanism reliably controls the flow of well fluids through the blowout preventer and may be automatically locked in an infinite number of locking positions within a wide locking range.

Blowout preventer with ram wedge locks

A hydraulically controlled blowout preventer 10 and method are disclosed for simultaneously moving two sealing assemblies 24, 27 to seal around an oilfield tubular 15 within the bore 14 of BOP 10. A single manual operator 20 may be rotated to simultaneously move master piston 26 and hydraulically interconnected slave piston 79 inwardly toward bore 14 or outwardly away from bore 14, respectively. BOP 10 is field convertible to purely hydraulic operation by disconnecting the threaded shaft 52 from master piston 26. Hydraulic lines 36 and 40 interconnect between cylinders 30 and 82 to result in simultaneous operation of seal assemblies 24, 27.

Hydraulically controlled blowout preventer

A ram assembly for positioning within a through bore of a blowout preventer body includes first and second opposing ram pistons each powering a respective knife blade. Each knife blade may have a pair of angled shear edges on opposite sides of the respective ram centerline, with each pair of angled shear edges defining a generally V-shaped configuration. The pair of opposing knife edges preferably engage the oilfield tubular at four contact points spaced substantially equidistant about a circumference of the tubular, and thereby contain the tubular for the shearing operation. According to the method of the present invention, the oilfield tubular is sheared substantially by brittle shearing rather than ductile shearing. By containing the tubular prior to shearing, the body of a shearing assembly may have a bore only slightly greater than the diameter of tubular to be sheared, thereby significantly reducing the costs and increasing the versatility of the shearing equipment, and also reducing the cost of the blowout preventer and the associated wellhead stack.

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Houston, TX, United States of America

David L O'Donnell