
The annular preventer, also known as an annular BOP, is a large, donut-shaped device installed at the top of the BOP stack. It uses a rubber sealing element reinforced with steel, known as a packing unit, which is hydraulically compressed to form a tight seal around the drill pipe or completely across the open wellbore. This action prevents the uncontrolled escape of formation fluids—such as oil, gas, or water—that could lead to a blowout.
Unlike ram-type BOPs, which require specific-sized rams to seal around different diameters of pipe, the annular preventer can accommodate a wide range of pipe sizes and shapes. This adaptability is one of its most significant advantages. Continue reading