Key Features

Fully redundant subsea electronics

Subsea units depth rated to 4,000 metres

Dual acoustic transceivers mounted on BOP ensure reliable communications with the surface

Compatible with all makes of BOP

Wideband signal technology ensures reliable operation in near BOPs

Drives up to 12 solenoid functions

Overview

The BOP control subsea system consists of a dual redundant Subsea Electronics Module (SEM) and two (expandable to four) Deep-rated Acoustic Remote Transceivers (DARTs). All housings are constructed from super duplex steel and the system is depth rated to 4,000m / 12,000 ft.

The DARTs are installed on arms, typically 8-10 feet long, that swing out from the opposite sides of the BOP stack. This ensures that they have an unobstructed ‘line-of-sight’ path to the surface for reliable acoustic communications. Both DARTs are connected to the SEM using oil-filled, pressure balanced cables.

The SEM provides the interface to the client BOP, driving up to 12 pilot valve solenoids to operate the BOP hydraulic functions and reading back up to 12 pressure operated status switches and 4 analogue sensors which indicate the internal status of the BOP. The SEM can interface to BOPs from all of the major manufacturers.

The dual redundant SEM can operate with up to four DART transceivers to provide multiple acoustic communication paths and ensure reliable communication even under the most demanding conditions. This level of acoustic and functional redundancy, combined with the inherent robustness of the Wideband signals achieves an acoustic link with reliability that is comparable to that of a cabled link and may be considered as a direct alternative to an umbilical cable.

System availability is ensured by a periodic ‘heartbeat’ signal sent automatically from the surface to the subsea system. The reply indicates the health of the system. There are also built-in test functions to test all pilot valve solenoids in the client’s BOP. All operations and communications are logged. The acoustic signalling uses sophisticated modulation and optimal correlation receiver processing to provide a two-way communication link that is highly robust and extremely resistant to noise, multi-path effects and interference from other acoustic sources.

Each installation has a unique address and will only respond to commands which include its address. This allows several systems to operate within acoustic range of one another without any mutual interference. The probability of a false trigger event has been shown by analysis and measurement to be extremely remote, whilst the probability of operation on demand has been similarly shown to be very high.