Brief introduction:

1. Use
Used in the hydraulic control system, close different size of the annular space when there are drilling tools in well. Fully close the annular space formed by Kelly bar, coring tool, cable, and steel wire rope and wellbore. In conjunction with the reducing and regulating pressure valve and buffer storage, can pass 18 degrees without fine buckle butt welding pipe, conduct the forced tripping operation.

2. Working principle
The annular BOP is operated by the hydraulic control system. When closing, high pressure oil from middle oil nipple of shell enter into the lower cavity of piston, pushing the piston upward, cone surface of piston squeeze the rubber core. Because of the limitation of the top, rubber core can't uplink only be pushed to the wellhead center, until hold drill tools or fully close the wellhead. Achieve the goal of closing the well.
When open the well, operate valve of hydraulic control system makes the high pressure oil from shell oil nipple enter into the upper open cavity of the piston, push the piston downward, close cavity and release pressure, then the extrusion pressure on the rubber core cone surface is removed, rubber core under its elastic force is reset gradually and open the wellhead.