Patent ID: 8162046
Filing Date: 2012-04-24
Classification: E21B

Abstract:
1. A blowout preventer (“BOP”) for an oil or gas well, comprising: a BOP body having a through-bore defining a centerline and adapted to allow a tubular member to be disposed therethrough, the body having at least a first guideway defining a guideway centerline formed at an angle to the through-bore centerline; a first ram slidably coupled to the BOP body along the first guideway for travel along the first guideway; a first shear blade coupled to the first ram toward the through-bore to shear the tubular member disposed therein, the first shear blade being disposed laterally across the first ram and having a first shear blade profile with a first portion on one side of the guideway centerline and a second portion on an opposite side of the guideway centerline from the first portion, the first portion and the second portion of the first shear blade profile being asymmetric from each other relative to the guideway centerline, wherein the first shear blade profile comprises a first stress concentrator, wherein the first stress concentrator is laterally offset from the guideway centerline; a second ram slidably coupled to the BOP body along a second guideway aligned with the first guideway; and a second shear blade coupled to the second ram and distal from the first shear blade relative to the through-bore, the second shear blade being disposed laterally across the second ram and having a second shear blade profile with a second stress concentrator that is laterally offset from the guideway centerline on an opposite side of the guideway centerline from the first stress concentrator on the first shear blade profile.