Dynamic Performance of Annular Blowout Preventer Hydraulic Seals in Deepwater Environments

Abstract

Presented is the performance analysis of annular blowout preventer (BOP) reciprocating elastomer hydraulic seals operating in subsea environments. The method is based on a systems-level model that combines the effects of friction, material mechanical properties of the seal, installation compression, subsea hydrostatic pressure, and control system dynamics into one model. The model is calibrated using data from tests conducted on the surface and then validated on subsea operational data. Through model simulations, it will be shown that insufficient installation squeeze of the seal in combination with low elasticity seal material results in cases where the seal does not leak at the surface but show substantial internal leakage in subsea conditions. Leakage is also observed under dynamic operation when the walls of the seal groove do not energize the seal. The proposed model-based analysis method in conjunction with surface level testing offers a new paradigm in evaluating reciprocating seal subsea performance a priori of subsea operation thereby avoiding costly downtimes and subsea failures.