US 5,400,857 A · Oilfield tubular shear ram and method for blowout prevention

Abstract

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.

Claims20

Dependent claims

A ram assembly for positioning within a guideway within the body of a blowout preventer having a bore therethrough for receiving an oilfield tubular, the ram assembly comprising:

first and second opposing ram pistons each linearly movable along a respective ram piston centerline between an open position for passing the oilfield tubular through the bore of the blowout preventer, and a closed position for shearing the oilfield tubular within the bore of the blowout preventer;
first and second opposing knife blades carried by the respective first and second opposing ram pistons, each knife blade having a pair of angled shear edges on opposite sides of the respective ram piston centerline for engaging the oilfield tubular, each pair of angled shear edges defining a generally V-shaped configuration having a knife blade apex;
and
each angled shear edge being positioned at an angle of from 27.degree. to 55.degree. with respect to a ray extending from the apex of the V-shaped configuration to the center of the bore of the blowout preventer, such that the opposing knife blades contain then shear the oilfield tubular.

1 more element

Dependencies are inferred from the claim text.

Oilfield tubular shear ram and method for blowout prevention

Life of this patent

Oilfield tubular shear ram and method for blowout prevention

Life of this patent

Abstract

Claims20