scope:

SCOPE

1.0 These specifications establish design standards for systems, subsystems and components used to control BOP's (blowout preventers) and associated valves that control well pressure during drilling operations. Although diverters are not considered well control devices, their controls are often incorporated as part of the BOP control system. Control systems for drilling well control equipment typically use stored energy in the form of pressurized hydraulic fluid (power fluid) to operate (open and close) the BOP stack components. Each operation of a BOP or other well control component is referred to as a control function. The control system equipment and circuitry varies generally in accordance with the application and environment. Thus, the specifications provided herein are applicable to six control system categories.

These include:

1.1 CONTROL SYSTEMS FOR SURFACE MOUNTED BOP STACKS. These systems are typically simple closed hydraulic control systems consisting of a reservoir for storing hydraulic fluid, pump equipment for pressurizing the hydraulic fluid, accumulator banks for storing power fluid, manifolding, piping and control valves for transmission of control fluid to the BOP stack functions.

1.2 HYDRAULIC CONTROL SYSTEMS FOR SUBSEA BOP STACKS. In addition to the equipment required for surface mounted BOP stacks, subsea control systems use umbilical hose bundles for transmission of hydraulic pilot signals subsea. Also used are dual subsea control pods mounted on the LMRP (lower marine riser package), housing pilot operated control valves for directing power fluid to the BOP stack functions. Spent water-based hydraulic fluid is usually vented subsea. Hose reels are used for storage and deployment of the umbilical hose bundles. The use of dual subsea pods and umbilicals afford backup security.

1.3 ELECTRO-HYDRAULIC/MULTIPLEX CONTROL SYSTEMS FOR SUBSEA BOP STACKS. For deepwater operations, transmission subsea of electric (rather than hydraulic) signals permits short response times. Electro-hydraulic systems employ multi conductor cables, having an individual wire dedicated to each function to operate subsea solenoid valves which send hydraulic pilot signals to the valves that operate the BOP stack functions. Multiplex control systems employ serialized electronically coded messages transmitted over shared conductors. Electronic data processing and transmission are used to provide the security of codifying and confirming functional command signals so that a stray signal, cross talk or a short circuit should not execute a function.

1.4 DIVERTER CONTROL SYSTEMS. Direct hydraulic controls are commonly used for operation of the surface mounted diverter unit and any associated valves.

1.5 EMERGENCY BACKUP BOP CONTROL SYSTEMS. When the subsea control system is inaccessible or nonfunctional, an independent control system may be used to operate critical well control and/or disconnect functions. These systems have their own supply of power fluid. They include acoustic control systems, ROV (Remotely Operated Vehicle) operated control systems and LMRP recovery systems. For surface control systems, a reserve supply of pressurized nitrogen gas can serve as a backup means to operate functions in the event that the pump system power supply is lost.

1.6 AUXILIARY EQUIPMENT CONTROL SYSTEMS AND INTERFACES. For floating drilling operations, various auxiliary functions such as the telescopic joint packer, 30′ latch, etc., require operation by the control system. These auxiliary equipment controls, though not specifically described herein, shall be subject to the relevant specifications and requirements for similar equipment.