Annular Preventers – Well Control Equipment

Annular preventers are the most versatile well control equipment and there are many names referring it as bag preventers, or spherical preventers. The annular preventers are able to seal around several size of drill pipe/drill collar, work string, wireline, tubing, etc. There are some models which can utilize wellbore pressure to provide additional sealing capability.

The annular preventer consists of a body, a cap, a piston and a rubber packing element. The illustration below demonstrates the drawing of an annular preventer.

How the annular preventers work?

Close – When the hydraulic oil is pumped into the extend port, the element inside will be lifted and squeezed the pipe/tubular.


Open – On the other hand, if the hydraulic fluid is pumped into the retract port, the element will be pushed down resulting in releasing the tubular.

The following videos will help you understand how the annular preventer work.



Nowadays, there are several manufactures providing this equipment such as Hydril, NOV (Shaffer) and Cameron. The models available in the market based on the manufactures are listed below:

Hydril – Hydril GL, GX, GK and Annu-Flex

Hydril GL

Hydril GL

Hydril GK

Hydril GK

Hydril Gx

Hydril Gx

Hydril Anuflex

Hydril Anuflex

Cameron – Cameron DL

Cameron DL

Cameron DL




In the market, the annular preventers have wide range of size and operating pressure and you can see from the technical specification from the link that we provide. It is very important that personnel must know how to operate and maintenance the annular preventers properly. Personnel must strictly follow the operating manual to prevent the premature failure.


Cormack, D. (2007). An introduction to well control calculations for drilling operations. 1st ed. Texas: Springer.

Crumpton, H. (2010). Well Control for Completions and Interventions. 1st ed. Texas: Gulf Publishing.

Grace, R. (2003). Blowout and well control handbook [recurso electrónico]. 1st ed. Paises Bajos: Gulf Professional Pub.

Grace, R. and Cudd, B. (1994). Advanced blowout & well control. 1st ed. Houston: Gulf Publishing Company.

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12 Responses to Annular Preventers – Well Control Equipment

  1. farley cabili says:

    good job drlingformulas!!:p

  2. Hesam says:

    I think you just made a mistake in showing the open and close port path way! ( The Red Arrow)

    Thanks for your good website

  3. Dewo says:

    I Have always find this website very usefull, specially your daily news letter. Good Job Guys keep up the Good work.
    However on this articels (annular preventers) I Think you may have made a small error on you Information on Opening and Closing Port, I think you got it backwards, Opening Shoild be from the top and Closing should be from the Bottom

    never the less.. this is a Fine website..

    Thank you

  4. Pradeep says:

    He guys what is range of anular closing pressure minimum to any update

  5. Jim Wight says:

    Where is the API monogram stamped on an annular BOP. is it stamped into the body of the BOP or just attached byan API plate
    My best regards
    Jim Wight

  6. Darcy says:


    Is a Hydril GX and GK (13 5/8 x 5 K) element compatable with each?



  7. Marek says:

    Annular Upetrom VH is a copy of Hydril GK.
    Head packer unit is the same?

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