Blow-out preventer(BOP) When drilling for oil, it is installed on the wellhead casing head to control high-pressure oil, gas and water blowout devices. When the oil and gas pressure in the well is high, the blowout preventer can close the wellhead (closed). When the heavy mud is pressed from the drill pipe, there are four links under the ram, which can replace the gas invaded mud and increase the pressure of the liquid column in the well to suppress the high-pressure oil and gas. Its type is divided into ordinary BOP, universal BOP and rotary BOP. The universal blowout preventer can be started in an emergency, and can deal with any size of drilling tools and empty wells; the rotary blowout preventer can perform spraying and drilling. In deep well drilling, in addition to two ordinary blowout preventers, plus universal blowout preventers and rotary blowout preventers, three or four combinations are installed at the wellhead. Annular Blow-out Preventer Large sluice gates usually equipped with ram-type blowout preventers will form a sealed annular space between the pipe string and the wellbore during operation. It can also be used alone in the case of a pipe string Completed well closure, but it will not work a few times, and it is not allowed to use the well for a long time.