Patent ID: 7367396
Filing Date: 2008-05-06
Classification: E21B,Y10T

Abstract:
1. A method for severing an oilfield tubular, the oilfield tubular useful for wellbore operations, the method comprising inserting a tubular into a blowout preventer, the blowout preventer including a tubular severing apparatus comprising a first shear ram block movable toward the tubular, a second shear ram block movable toward the tubular, a first blade on the first shear ram block, the first blade comprising a first blade body, a first projection projecting from the first blade body, a first point structure on the first projection for contacting and puncturing the tubular, first projection cutting surfaces on the first projection defining the first point structure and for cutting the tubular, the first projection cutting surfaces at an acute angle to each other, the first point structure having a single point comprising a first point, the first point structure projecting sufficiently from the first blade body so that the first point contacts the tubular and punctures the tubular before any other part of the first blade body contacts the tubular, and a second blade on the second shear ram block, the second blade comprising a second blade body, a second projection projecting from the second blade body, a second point structure on the second projection for contacting and puncturing the tubular, second projection cutting surfaces on the second projection defining the second point structure and for cutting the tubular, the second projection cutting surfaces at an acute angle to each other, the second point structure having a single point comprising a second point, the second point structure projecting sufficiently from the second blade body so that the second point contacts the tubular and punctures the tubular before any other part of the second blade body contacts the tubular, the first projection disposed above and opposite the second projection, moving the first blade toward the tubular to bring the first point structure into contact with an outer surface of the tubular, moving the first blade so that the first point structure punctures into the tubular, moving the first blade to cut a portion of the tubular with the first projection cutting surfaces, moving the second blade toward the tubular as the first blade is moved toward the tubular and moving the second blade so that the second point structure contacts an outer surface of the tubular, moving the second blade so that the second point structure punctures into the tubular, moving the second blade to cut a portion of the tubular with the second projection cutting surfaces, and severing the tubular by moving the first blade and the second blade toward the tubular.