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When a well kick occurs, the high-pressure oil from the
control system, through the oil inlet at the lower part
of the case, enters the lower shut-off chamber of the
piston, and push the piston to move up and makes the
rubber-ram move up along the spherical surface. That
makes the supporting ribs close and squeeze the rubber
to the center, in order to carry out the sealing off
drilling tools or shutting the whole well. During
opening well, the piston is moved down by hydraulic
system, and rubber-ram recovers under the action of
itself elasticity, and opens the well.
In the unique design of the annular BOP, closing
pressure forces the operating piston and pusher plate
upward to displace the solid elastomer donut and force
the packer to close inward. As the packer closes, steel
reinforcing inserts rotate inward to form a continuous
support ring of steel at the top and bottom of the
packer. The inserts remain in contact with each other
whether the packer is open, closed on pipe or closed on
open hole.
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