System and Method for Rescuing a Malfunctioning Subsea Blowout Preventer

Abstract

A pair of rescue vehicles are deployed on deployment cables to force the shear ram of a sub-sea BOP to shut if it should malfunction. The rescue vehicles may be provided with a camera for remote operation from the surface. The rescue vehicles include securing arms to mate with receiving means on the BOP or its enclosure. The securing arms actuate hydraulic means to release the BOP shear ram piston from hydraulic lock. The rescue vehicles carry their own hydraulic fluid under pressure, or hydraulic fluid pressure may be supplied from the surface or from an ROV, in order to actuate a rod which strikes the accessible BOP shear ram tail rod, forcing the shear ram shut. The rescue vehicles also carry their own securing wedges to slide down behind the vehicle rod, securely holding the BOP shear ram shut.

Description

FIELD OF THE INVENTION[0001]The present invention relates generally to the field of sub-sea blowout preventers and, more particularly, to a system and a method for assisting the shutting of such a blowout preventer should it fail to properly shut.BACKGROUND OF THE INVENTION[0002]A blowout preventer (BOP) for deep subsea oil and / or gas well work is commonly hydraulically operated. The hydraulic pressure may be electrically generated downhole or provided from a surface source. Commonly used hydraulic control valves require electrical power to actuate. The signal for actuation may be by way of a hard wire, an acoustic signal, or by radio frequency signal transmission. Failure of any of (1) power to supply the hydraulic pressure, (2) the signal circuit, (3) any of several control valves, or (4) leakage of hydraulic fluid supply will render the BOP inoperative.[0003]Such a BOP is provided for subsea drilling operations which may experience a blowout, i.e. an uncontrolled flow of formatio...

AI Technical Summary

Problems solved by technology

Failure of any of (1) power to supply the hydraulic pressure, (2) the signal circuit, (3) any of several control valves, or (4) leakage of hydraulic fluid supply will render the BOP inoperative.

A blowout can cause loss of life, pollution, damage to drilling equipment, and loss of well production.

While the system proposed by Donohue et al. does indeed provided additional operational redundancy, it is not effective in shutting a malfunctioning shear ram if the problem is not of the type requiring hydraulic backup.

For example, if the hydraulic system is still intact, but the shear ram failed to shut because it was jammed or otherwise failed to shut, then the system of Donohue et al. would be ineffective.

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