Shear Rams: shear ram
A blowout preventer (BOP) closing element fitted with hardened tool steel blades designed to cut the drillpipe when the BOP is closed. A shear ram is normally used as a last resort to regain pressure control of a well that is flowing. Once the drillpipe is cut (or sheared) by the shear rams, it is usually left hanging in the BOP stack, and kill operations become more difficult. The joint of drillpipe is destroyed in the process, but the rest of the drillstring is unharmed by the operation of shear rams.
Shear-seal BOP (Blind Ram)
An item of pressure-control equipment often fitted to the wellhead during well-intervention operations on live wells. Most commonly associated with coiled tubing operations, the shear-seal BOP is a ram-type preventer that performs the dual functions of shearing or cutting the tubing string and then fully closing to provide isolation or sealing of the wellbore. Shear-seal BOPs are most commonly used in offshore or high-pressure applications where an additional contingency pressure barrier is required.
Annular blowout preventer:
A large valve used to control wellbore fluids. In this type of valve, the sealing element resembles a large rubber doughnut that is mechanically squeezed inward to seal on either pipe (drill collar, drillpipe, casing, or tubing) or the openhole. The ability to seal on a variety of pipe sizes is one advantage the annular blowout preventer has over the ram blowout preventer. Most blowout preventer (BOP) stacks contain at least one annular BOP at the top of the BOP stack, and one or more ram-type preventers below. While not considered as reliable in sealing over the openhole as around tubulars, the elastomeric sealing doughnut is required by API specifications to seal adequately over the openhole as part of its certification process.
More oilfield drilling definitions:
http://www.glossary.oilfield.slb.comCameron is the company that makes BOPs:
BOPs on the Deep Horizon well-
BOP 2 x Cameron Type TL 18¾in 15K double preventers;
1 x Cameron Type TL 18¾in 15K single preventer;
1 x Cameron DWHC 18¾in 15K wellhead connector
http://www.deepwater.com/fw/main/Deepwater-Horizon-56C17.html?LayoutID=17Cameron site:
http://www.c-a-m.com/index.cfm#More than you ever wanted to know. None of it worked.