This paper presents the design development carried out by Deep Sea Production Systems (DSPS) since 1977 to develop seabed hydrocarbon production and processing systems for use in deep water. Designs for a variety of applications have been developed for water depths down to 1000 metres. They comprise one or more seabed pressure hulls providing a dry one-atmosphere environment in which to house production and process equipment. The chambers are operated and maintained using a combination of remote control from the surface and manned intervention at the seabed.
As well as providing a valuable means of deep water production the one atmosphere system is shown to offer a viable means of exploiting marginal satellite reserves in relatively shallow water by manifolding the flows and commingling them to a central platform some distance away for processing.
Reference designs are described for a total deepwater "Seabed Production System" serving a 100,000 BOPD field in 500 metres of water and, secondly, for a "Satellite Manifold Chamber" serving an outlying reservoir producing 60,000 BOPD in 300 metres of water, ten kilometres from a central processing platform.
Although industry and governments are directing massive research and development funds towards renewable forms of energy such as solar, wind, wave and tidal power, the vast bulk of the world's energy needs over the next decades will probably be met by oil and natural gas. These hydrocarbon reserves now supply about 70 per cent of the western world's energy, and most authoritative sources predict the proportion will only have been reduced to 60 per cent by the year 2000.
To meet this long term requirement the search for oil and gas is extending into deeper and more hostile waters, sometimes with the added difficulty imposed by severe surface ice conditions.1
The main engineering difficulty associated with production of these deepwater reserves is not the drilling and completion of the wells - this can be accomplished from floating vessels which are able to remain on station in all but the most severe weather conditions - but rather, in deciding how best to house the permanent production and process equipment. The severe cost and technical restraints of providing surface facilities in very deep and hostile waters has led DSPS to develop a system which operates on the seabed, thereby reducing the difficulties of water depth and surface environmental conditions.
This work started in 1977 and receives financial support from the European Community and the U.K. Department of Energy. Phase I, which is now completed, evaluated the technical feasibility of a variety of seabed applications in water depths down to 1000 metres. The main application developed was for a total "Seabed Production System" comprising five large seabed chambers linked together to provide a complete seabed facility for manifolding, separation, water injection and gas compression. A tanker loading facility has been included which supports surface facilities for power generation and remote control capability. Detailed estimates of both capital and operating costs have been encouraging and more detailed development of key areas is being continued in the current Phase II programme which is due for completion in 1982.
