摘要 |
A hydraulically-operated annular blowout preventer, for controlling a wellbore and comprising a wiper seal assembly, is described. The wiper seal assembly comprises a discrete wiper seal, for preventing debris and/or contaminants from the wellbore from entering the hydraulic fluid chamber of the blowout preventer, a discrete pressure seal, positioned below and abutting the wiper seal in the same seal groove, for isolating the hydraulic chamber, and a retainer member for preventing both radial and axial movement of the wiper seal.
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