A trend within to-days contracting market is the desire for more local value creation, as expressed by requirement for significant local content for large offshore development. With the industry mostly adapted to module fabrication this poses challenges for deep water development.

So far FPSO's has been best suited to accommodate the modular topside layout. However other requirements related to e.g. minimum motions from a riser point of view or the request for dry wellhead indicate that column stabilized units e.g. semis or TLP's may be the most suited concept from an operational point of view.

This paper describe how column stabilized units can be reconfigured and optimized to hold its position as the workhorse of the deep-water field developments by implementing a module support frame, and a modularization of the facilities.

The concept has been development in connection with a study for a large deep-water field and has been benchmarked with more conventional integrated deck structures for semisubmersibles. Focus was put on the overall configuration of the floater to be able to accommodate a modularization of the facilities without significant onerous impact on payload capacity, size and motion behavior of the semisubmersible.


The semisubmersible has during the last decade secured its position as the workhorse for large oil and gas field developments in medium to deep waters. For a majority of these developments integrated deck structures in different variants has been implemented since it generally results in the lightest topside and therefore also the smallest hull. The platforms has mainly been developed for Norway and for the Gulf of Mexico where the oil companies, the design office and the construction site all have long experience being able to handle the complexity involved in large integrated deck structures. In other regions the module topside facilities may be more adaptable to the local industry and infrastructure. It is however important to understand that it is not only technical issues that is of importance, but also subject like the contract models and the capabilities of the local industry and especial the yards when selecting the concept for a field development.

Contract models

The contract model used for large offshore structures varies with time, region and also from project to project depending on who is the developer. Although, the oil company in charge of the development is responsible for the contract model it is important that the capability of the local industry to be utilized is suited for the preferred contract model.

Typically in Norway the industry has developed from an Engineering Procurement (EP) and Fabrication Contract (FC) regime in the eighties and early nineties to an Engineering Procurement Construction and Installation (EPCI) or Engineering Procurement Construction management (EPCm) regime where a single contractor has a majority or all responsibility for the platform design procurement and construction. The transformation from one regime to the other was very challenging and resulted in significant losses for both developer and contractor and has further resulted in a reorganization of the Norwegian offshore industry.

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