The Hydril GK annular blowout preventer (Figure 1A & B) is the most common annular preventer in use in drilling rig, particularly in surface stack installations, and is unique in its response to well pressures. Therefore the most commonly used types will be discussed. There are some differences in the operation of the various annular preventers. This arrangement is recommended for all surface and subsurface stacks. annular preventer, to allow for hydraulic fluid movement when stripping, is very desirable from the viewpoint of reducing packing unit wear.The arrangement where a small accumulator bottle (surge bottle) is placed in the closing line of the It is very important to see to it that this regulator is in good shape, that there are no check valves ahead of it (often present in the four-way valve), or that it has been replaced by a plain regulator. That way the packing unit can open against the closing pressure while stripping a tool joint. The regulator valve in the drilling rig that used to regulate the annular preventer closing pressure should allow fluid passage back through it if the line pressure increases. The small lines and/or restrictions make the packing unit movement inflexible when trying to strip, and cause excessive packing unit wear during stripping operations, especially when tool joints are passing through it. In addition, it increases the wear on the packing unit. Raising the closing pressure does not help as much as using larger lines and fittings. Even though current regulations specify a 38 mm minimum diameter hydraulic control line, many surface stacks may still have hydraulic lines to (1112′ 1) the annular preventer that are smaller or have a restriction in them which prevents rapid closing. The annular preventer takes three to ten times the volume of fluid to close, compared to a set of rams, and therefore requires a longer closing time. The closing time of annular BOP preventers The main disadvantage of the annular preventer in drilling rig is the time required to close it. Biggest Oil Rigs Top 5 Mighty Structures.Spare packing units should be stored in a dark, cool room.Motion reversal is hard on the packing unit, so pipe should be moved as far as possible in one direction before reversing the direction (i.e.Closing the annular preventer without pipe in the hole will shorten the life of the packing unit, especially when high closing pressures are equired to achieve this.Testing the annular preventer under high test pressures significantly shortens the life of the packing unit.The closing pressure as regulated through the control system should be as low as practically possible in order to maximise the life of the packing unit.The following factors influence the life span of annular preventers: Here, we will cover all annular blowout preventer BOP types as Cameron, Hydril & Shaffer BOP types that are used in drilling rig. Treated properly, the packing unit of the annular preventer has a long, reliable life span, but it can be destroyed in a very short time or very few closing cycles by improper use. The rubber packing elements of the annular preventers, which allow this flexibility, are also subject to wear and abuse.
The annular preventer (also called bag type, spherical or universal preventer) is the most versatile piece of equipment on the BOP stack since it can close around the casing, drill pipe, drill collars, wireline, and even close an open hole.
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