Annular blowout preventer

Used in conjunction with hydraulic control system,the annular BOP seals off the annulus of different sizeswhen drilling tool

Used in conjunction with hydraulic control system, the annular BOP seals off the annulus of different sizes when drilling tool is set in the hole, when there is no drilling tool in the hole, it can also seal off the wellhead. If well blowout happens during the coring and measur-ing operation, it can seal off the annular spaces beteenthe well barrel and kelly, coring tool, cable and steelrope etc. matched with pressure-relief valve and buffertank, it can force-execute the running/retrieving drilloperation through butt-weld drilling-rod at 18 degreewithout fine thread.

2.Working Principles

A hydraulic control system is used to close or open the annular preventer. when it is closed, high pressure oil is directed to the closing chamber positioned in thelower side of the piston, causing the piston to moveupward. The rubber core is compressed by the movingpiston. Because the annular BOP has a cap, the pack-ing unit can not move upward and only can move to-ward the center of the well to pack off a string or seal off the well.

When well open is required, operate the reversalvalve to direct high pressure oil from the upper oil-portinto the chamber in the upper side of the pistion so asto push the pistion to move down, and then the closingchamber is relieved, the squeese pressure at the coneof rubber core is removed, the wellhead is opened

3.Operating Requirements:

(1) The annular BOP can be used to seal off a wellwhere the drill pipe is in use if the well blowout.However, the annular BOP cannot be closed for along time, because the packing unit is easy to bedamaged and the BOP itself has no lockingmechanism.

(2) It is necessary to use a drilling tool with 18 bevel when running/retrieving drill of operation with BOP,running/retrieving drill should be slow pass throughthe nipple and all the rubber protecting collar onthe drilling tool should be discharged off.

(3) With the annular BOP in the closed position andshut-in pressure kept below 5MPa, the string canbe moved either up or down, but mustn't be rotated.

(4) It is forbidden to open the annular BOP to relievethe pressure out of the well to avoid rubber core damage.

(5) Be sure to check whether the annular BOP is inthe full open position or not every time after openedin order to prevent damage to the packing unit.

(6) Clean the inside of the BOP after well cementingoperation is completed in order to keep its clos-ings and openings flexible.

(7) More attention shall be paid to ring gaskets andgasket grooves during installation of the BOP or itsremoval from the service

(8) After entering the destination layer, running/retriev-ing drill once should be accompanied with test ofwell-enclosed with drilling tool once, and inspectthe effect of well enclosed with rubber core, if be-yond the requirement, it should be replaced.

(9) Periodically perform pressure test on the annularBOP in accordance with applicable standards.

Annular blowout preventer