It is BP Exploration's declared objective to develop a diverless subsea production system (DISPS), to bring on stream a subsea field in water depths beyond diver access by the md-1990s. With application centred on UKCS 9th Round licenses, the DISPS Project team wthn BPX has started on a programme of engineering, development and testing to provide the necessary technology. In the early stages of Phase 1 of the programme, equipment reliability has been emphasised with work on component qualification and upgrading, reliability modelling and system testing.

The system of modules has been configured for maximum reliability and independent retrieval of least reliable components. Optimization of the system will continue throughout-the Phase 1 programme. The system design includes several features Intended to aid operation of the remote production facility, such as downhole pressure monitoring. Concentric tubing hangers are involved to ease the problems of orientation and guidance of drilling and workover risers in deep water. Various contracts are in place with designers of equipment, handling systems and control architecture, and further contracts are in preparation for component development.

Plans for Phase 1 continue after component development with onshore and offshore testing of modules and handling systems, to be completed m 1989. In Phase 2, a prototype system will be installed and used to produce oil in diver-accessible depths, probably exporting to a fixed platform. This full-scale trial will give BP operational experience over several years, and the confidence to specify a diverless system for production to a fixed or floating structure by 1995. Work is continuing to review DISPS application to a range of conditions and to ensure that the work programme correctly reflects BP exploration and development strategy.


It is BPX's declared objective to develop a diverless subsea production system for operational service in the mid 1990s in water depths in excess of 350 m. In the region west of Shetland, BP holds licenses under the UK 9th Round to drill as operator and in other blocks as co-venturer. Many of these blocks lie on the continental slope where depths between 300 and 800 m are typical. Clearly, our ability to exploit any hydrocarbons found in these technically difficult regions relies on having the production technology in place. One of the immediate consequences of the deepwater exploration programme is the step into diverless technology at the c 350 m limit; at least, the economics of diver access at c. 400 m become very unattractive. In view of the cost of the deepwater diverless technology the field sizes in prospect must be large and flow rates high to justify the long development programmes. Looking back to 1965 at over 300 wildcat wells drilled by the industry in depths ranging from 200 to over 2000 m, about 60 have been in water depths exceeding 600 m. Very little success has been achieved in depths exceeding 600 m. Consequently, BP's subsea production system technology is centred on 400 m water depth.

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