Annual Blowout Preventer

Working principle of the Annular Blowout Preventer

The annular blowout preventer is operated by the hydraulic control system. When it’s closed, high pressure oil comes from the middle oil part of the shell into the lower closing cavity of the plunger, pushing the plunger upward, and cone plunger squeezes the rubber core, because of the limitation of the top cover, rubber core can’t uplink but can only be pushed to the center of the well, until hold drilling tools or close the whole wellhead to achieve the goal of sealing the well.

When the well is needed to open, directional control valve in hydraulic control system shall be operated, which makes high pressure oil come from the upper part of the shell to upper open cavity of plunger, promote the plunger downward, and close cavity to discharge pressure. The extrusion pressure in rubber core is eliminated, and then the rubber core is gradually reset under the elastic force of itself, thus opening the wellhead.

Operating requirement
  • When blowout takes place in well where there are drilling tools, firstly one can use annular blowout preventer to control wellhead, but try not close for a long time ,For one thing, the plastic core is easy to damage, for another, there is no locking device. It is not used to seal the empty well unless in special circumstances.
  • Tools with 18 degrees of inclined slope must be used in stripping operations with annular blowout preventer. When a joint is met, slow the speed of trip .All the rubber protectors on the drill shall be uninstalled.
  • When annular blowout preventer is in a closed state, the shut-in pressure shall be under 5 Mpa. Drilling tools can be moved up and down, but rotation is prohibited.
  • It is forbidden to drain borehole stress by way of opening the annular blowout preventer, in order to protect the rubber core from being stabbed.
  • Each time when the well is opened , it must be checked whether it is fully open to prevent tearing rubber core.
  • After well cementing and leakage operations, the lumen shall be rinsed, and keep the switch flexible.
  • When installing or removing he annular blowout preventer ,one shall pay special attention to the seal ring and steel ring groove, and damage or scratch is not allowed.
  • After entering the objective layer, one should take drilling toll to shut-in the well with rubber core. If it does nit meet the requirement, replace it immediately.
  • According to relevant standards, pressure of wellhead annular blowout preventer shall be tested regularly.