blow-out preventer (BOP)
BOP is shut in the well for oil testing, workover, well completion and operating process to prevent the blowout accident, totally enclosed and semi-closed two functions into one, has a simple structure, easy to operate, resistant to high-pressure characteristics is used to prevent blowouts safety oilfield sealing wellhead.
Oil drilling, installed at the wellhead casing head, used to control the high pressure oil, gas, water blowout. Wells of oil and gas pressure is high, the BOP can be the wellhead closed (shut). The shutter has four, alternatively bullied invaded mud, increasing the pressure of the borehole fluid column, so as to suppress the high-pressure oil and gas discharged from the drill pipe is pressed into the heavy mud.
Its type sub-ordinary blowout preventer, of universal blowout preventers and rotating blowout preventer. Ordinary BOP ram with full-and semi-closure, full closure type blowout preventer can seal the entire wellhead; semi-sealed shut wellhead annular cross-section of drill pipe exists. Universal BOP can start in case of emergency to cope with any size drill and empty wells; the rotating BOP side spray edge drilling operations. In addition to the outside two ordinary BOP, plus Universal BOP, rotating BOP, so three or four combinations installed at the wellhead deep drilling often. [1] annular BOP
Annular Blowout Preventer
  Annular BOP
Large gate, usually fitted with a ram type blowout preventer operation to form a sealed annular space between the tubing string and the wellbore in the well, baa case of a column-plugging can also be done individually, but used several times to die, and does not allow the use of long-term shut-in.
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Main criteria

SY / T 5053.1 -2000 BOP and control device BOP SY / T 5053.2-2007 drilling wellhead control equipment and the shunt device control system specification
SY / T 6160-2008 BOP inspection and maintenance