The Annular blow-out preventer often known as Annular BOP, Annular Preventer or occasionally Hydril Preventer, is a large valve that sits at the top of a BOP stack during drilling operations, used to control drilling fluids.
The annular BOP gets its name from the rubber annulus or doughnut shaped sealing element that compacts around the drill pipe by mechanical compression.
Its advantage over a Ram BOP is that it is able to seal around any pipe or tool differing in size or irregular surface, bit it drill pipe, drill collar, casing, tubing packers or guns.
The slide below shows the annulus sealing element out of the BOP, a cutaway of the Annular BOP with sealing element in place and the Annular BOP in its working state on top of the BOP stack.
Below is an animation showing the workings of an Annular BOP.
Last updated on 09:17PM - 22/08/16