A subsea blowout preventer (BOP) system is critical in providing safe working conditions for drilling activities in deepwater oil exploration. However, performance evaluation of the shear ram BOP is still a challenge for the industry. In this paper, two aspects of BOP shearing capability are studied: The required shear force to cut the pipe inside BOP successfully and the time it takes to shear the pipe and close the well. A finite element model is used to calculate the maximum shear force of a typical drillpipe, while an analytical hydraulic model is proposed to calculate the BOP closing time. A case study is presented for estimating the emergency disconnect sequence time in a deepwater offshore scenario. It is assumed that the BOP control system is activated from the surface, employing an electrohydraulic multiplexed control device for closing the BOP and rapidly disconnecting the lower marine riser package (LMRP), thus preventing damage to both riser and wellhead.

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