Deep water subsea production technology is probably the most rapidly advancing area in the field of offshore engineering.
The considerable efforts devoted to improve and optimise subsea equipment reliability and maintainability have culminated in the evolution of a new generation of modularised template and template component designs; these require new intervention tools and support vehicles and the market has been quick to respond with suitable system designs.
The impact of this rapid development of subsea equipment and corresponding maintenance intervention equipment design upon topside requirements on floating production facilities has, by and large, remained unrecognised by vessel designers and builders; conventional offshore drilling vessel designs still predominate.
Detailed assessment of anticipated subsea maintenance requirements and related facets of offshore operations has highlighted the significant economic benefits emanating from the provision on a floating production facility of at least a simple work string derrick, and preferably, full workover facilities. Integration studies must be undertaken in which subsea equipment design and topside maintenance support requirements are fully evaluated to achieve an optimised floating production facility.
It is generally considered within the Oil Industry that the majority of large hydrocarbon discoveries, in currently accessible offshore locations, have been discovered and that significant emphasis must now be given to the development of effective means of producing marginally economic hydrocarbon deposits, and those located in deep water, hostile environmental locations. The application of floating production facilities in association with subsea completed wells to develop such discoveries is an area in which considerable attention is currently being focussed.
The deployment of a floating production facility, especially in deep water, requires thorough evaluation on a total field development basis, embracing platform anchoring systems and motion characteristics, production and export riser systems through to the subsea completed wells. Installation and maintenance of subsea equipment, together with limited deck area and payload capacity, are factors which can have great influence upon the technical and economic feasibility of floating production facilities.
Several studies have been conducted into the development of subsea multiwell template systems for operation in conjunction with both floating and fixed processing facilities. These have, by and large, concentrated upon the absolute need to integrate the design of subsea equipment and associated maintenance intervention vehicles and tools; the necessary degree of emphasis has not always been given to the optimisation of topside support facilities for subsea maintenance intervention tasks and the attendant space and payload constraints that such requirements can impose upon a floating production facility.
When a dedicated field surface support facility is provided such factors need not be so extensively evaluated. However, in field developments for which dedicated facilities cannot be justified on economic or other grounds, the impact of subsea maintenance intervention requirements can have a dominant effect upon a floating production facility and, in the ultimate analysis, on field development economics generally.
