What is the working principle of the conical rubber core annular spray preventer?

When the conical rubber core annular blowout preventer performs the well closing action, the pressure oil from the hydraulic control system enters the lower oil chamber (i.e. closes the oil chamber) in a relatively rapid manner, and then pushes the piston to move rapidly upward. During this process, due to the limitation of the top cover, the rubber core cannot move upward. Under the action of the conical surface inside the piston, it is forced to squeeze and compact towards the center of the wellbore, thus surrounding the drilling tool and achieving the goal of closing the annular space at the wellhead. If there are no drilling tools in the well, the rubber core will continue to be squeezed and compressed towards the center until the hollow part of the rubber core is completely filled with rubber, thus achieving a fully sealed wellhead. At the same time, the hydraulic oil in the upper oil chamber slowly flows back to the oil tank through the hydraulic control system pipeline.

When the conical rubber core annular preventer is opened, the pressure oil from the hydraulic control system also enters the upper oil chamber (i.e. the opening oil chamber) in a relatively rapid manner, pushing the piston to move rapidly downward. In an instant, the squeezing force of the inner cone of the piston on the rubber core will completely disappear. The rubber core, relying on the elasticity of its own rubber, will stretch outward and gradually return to its original state, and the wellbore will then be fully opened. At the same time, the hydraulic oil in the lower oil chamber slowly flows back to the oil tank through the hydraulic control system pipeline.