Multi-point blade and pocket blade for a shear ram in a blow-out preventer

Abstract

A pair of blades in a shear ram of a blow-out preventer for cutting a tubular includes an upper blade and a lower blade. The lower blade shears the tubular in concert with the upper blade, the lower blade having a multi-point geometry to initiate shearing the tubular. The upper blade guides the tubular into a pocket-like geometry opposite the multi-point geometry of the lower blade. A blow-out preventor includes a blind ram, a shear ram, and a pipe ram, each including two ram blocks configured to extend into a bore to seal a bore. The shear ram includes an upper blade and a lower blade, where the lower blade shears the tubular in concert with the upper blade, the lower blade having a multi-point geometry to initiate shearing the tubular, the upper blade to guide the tubular into a pocket-like geometry opposite the multi-point geometry of the lower blade.

What is claimed: 
     
         1 . A pair of blades to be provided in a shear ram of a blow-out preventer for cutting a tubular, the pair of blades comprising:
 an upper blade; and   a lower blade configured to shear the tubular in concert with the upper blade, the lower blade having a multi-point geometry configured to initiate shearing of the tubular,   wherein the upper blade is configured to guide the tubular into a pocket-like geometry opposite the multi-point geometry of the lower blade.   
     
     
         2 . The pair of blades as in  claim 1 , wherein the multi-point geometry of the lower blade comprises two or more points. 
     
     
         3 . The pair of blades as in  claim 2 , wherein the multi-point geometry of the lower blade has two points. 
     
     
         4 . The pair of blades as in  claim 2 , wherein the two or more points are created by inward facing surfaces that descend from one or more jutting edges into the lower blade to form a V-like shape. 
     
     
         5 . The pair of blades as in  claim 1 , wherein the pocket-like geometry of the upper blade comprises two jutting edges with a flat leading surface located between the two jutting edges. 
     
     
         6 . The pair of blades as in  claim 1 , wherein the upper blade is housed in an upper block with two upper guide arms opposite one another on the upper block and located on a plane parallel-to and below the plane of the upper blade, wherein the two upper guide arms are configured to assist in tubular centralization and counteract tubular expansion. 
     
     
         7 . The pair of blades as in  claim 1 , wherein the lower blade is housed in a lower block with two lower guide arms opposite one another on the lower block and located on a plane parallel-to and below the plane of the lower blade, wherein the two lower guide arms are configured to assist in tubular centralization and counteract tubular expansion. 
     
     
         8 . A blow-out preventer comprising:
 a blind ram;   a shear ram; and   a pipe ram, wherein the blind ram, the shear ram, and the pipe ram each comprise two ram blocks configured to extend into a bore to seal the bore; and   wherein the shear ram comprises:   an upper blade; and   a lower blade configured to shear the tubular in concert with the upper blade, the lower blade having a multi-point geometry configured to initiate shearing of a tubular,   wherein the upper blade is configured to guide the tubular into a pocket-like geometry opposite the multi-point geometry of the lower blade.   
     
     
         9 . The blow-out preventer as in  claim 8 , wherein the multi-point geometry of the lower blade comprises two or more points. 
     
     
         10 . The blow-out preventer as in  claim 9 , wherein the multi-point geometry of the lower blade has two points. 
     
     
         11 . The blow-out preventer as in  claim 9 , wherein the two or more points are created by inward facing surfaces that descend from one or more jutting edges into the lower blade to form a V-like shape. 
     
     
         12 . The blow-out preventer as in  claim 8 , wherein the pocket-like geometry of the upper blade comprises two jutting edges with a flat leading surface located between the two jutting edges. 
     
     
         13 . A method of shearing a tubular, comprising:
 positioning the tubular in a cavity of a blow-out preventer, within a shear ram, between an upper blade and a lower blade,
 wherein the lower blade has a multi-point geometry, and 
 wherein the upper blade has a pocket-like geometry opposite the multi-point geometry of the lower blade, 
   actuating the shear ram, the actuating comprising moving the lower blade to shear the tubular in concert with the upper blade,
 wherein the pocket-like geometry holds the tubular within a containment zone within the pocket-like geometry, and 
 wherein, while the tubular is held within the containment zone, at least one point in the multi-point geometry contacts and initiates the shearing of the tubular by concentrating forces at the at least one point to locally tear the tubular at the at least one point. 
   
     
     
         14 . The  method of 13 , further comprising containing the tubular within an inner profile of the cavity using guide arms positioned on opposite sides of the pocket-like geometry, wherein the guide arms prevent expansion of the tubular out of the pocket-like geometry during shearing.