One of the first pieces of safety equipment designed for oil and gas production, the blowout preventer (BOP) is a large valve at the top of a well that can be closed if the drilling crew loses control of oil or natural gas while drilling or performing a work over. If these fluids manage to enter the wellbore, they may threaten the safety of the rig and crew. The BOP is designed to either close an open wellbore, seal around tubular components in the well, or cut through drillpipe. The crew can then increase the drilling mud density until it is safe to open the BOP, and drilling operations can resume. BOPs are tested regularly to ensure safety of the crew, rig, and wellbore.Types of BOP: The first ram BOP was controlled manually, and quickly became an industry standard. Early BOP designs could withstand pressures up to 3,000 psi. Today's average BOP can withstand 15,000 psi in water depths up to 10,000 ft. Another type of BOP is an annular BOP, also known as a spherical BOP, designed with a semicircle-shaped piece of rubber reinforced with steel to close around the drill
string as it moves up and in. While the basic concept of the BOP structure is the same, subsea BOPs have an added locking mechanism, which allows the crew to close it hydraulically. Deepwater subsea control systems remotely power seabed BOP valves and monitor the chokes and gauges in the system.There are currently 10 BOP manufacturers with BOPs working offshore. Cameron leads the pack with approximately 422 BOPs working on offshore rigs, Hydril has about 272, and Shaffer rounds out the top three with 248.
Cameron has unveiled the world's first 18 3/4in. 20,000 psi working pressure blowout preventer at the Offshore Technology Conference (OTC) in May 2009. The 18 3/4in. 20,000 psi working pressure EVO blowout preventer, right, was designed to meet the challenges of higher pressures and higher temperatures. The new 20,000 psi EVO BOP just finished qualification tests. (RigZone, 11/9/09)
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