找考题网-背景图
单项选择题

A.annular blowout preventerB.annulusC.accumulatorD.auto……

A large valve,usually installed above the ram preventers,that forms a seal in the annular space between the pipe and wellbore or,if no pipe is present,on the wellbore itself is called the().

A.annular blowout preventer
B.annulus
C.accumulator
D.automatic choke