As the focus of the offshore industry moves increasingly towards deepwater, attention is concentrating more and more on Me-cycle field development costs. Key elements are reducing development lead times, equipment standardisation and efficient use of scarce resources. An essential precursor is a clear definition of the metocean environment. Without it, engineering design may be unnecessarily conservative or inadequate. Either way the consequences will be expensive. It is the metocean challenge to help bring down costs while maintaining adequate safety levels, by providing the necessary answers but most important of all to do this in sufficient tune to be in step with the engineering requirements at each stage of a planned development.
The focus of the offshore oil and gas industry is increasingly moving towards deepwater. This presents new and exciting challenges across the technology spectrum. The purpose of this paper is to look specifically at the metocean (meteorological and oceanographic) issues and challenges associated with this move towards deepwater exploration and field development.
A brief review is given of deepwater prospects and developments around the world, and of some of the deepwater concepts being applied or considered. A cornparison is made of the relative metocean conditions that need to be designed for and considered when estimating potential workability. The relative contribution of waves, current and wind to overall loading is examined, in particular for tropical areas experiencing strong currents. Where metocean fits into the overall process of deepwater development is defined and the key drivers identified. The paper goes on to discuss some of the specific metocean challenges relating to deepwater, considering such issues as shelf edge currents, current profiles, seasonal and annual variability in conditions, as well as the El Nino and the North Atlantic Oscillation climate indicators.
Finally, the paper links these issues with the overall requirements for metocean information at each stage in the field development process - from initial concession evaluation right through the process to field abandonment. It examines the recent trend to begin metocean data collection in deepwater areas much earlier in the process than previously, frequently in advance of exploration drilling. Also it looks at the concerted effort to streamline the process to provide cost-effective ‘just-m-tune’ delivery of the required metocean advice and criteria. In conclusion, the critical success factors for the future highlighted.
Worldwide, there is now a significant portfolio of offshore concessions in water depths beyond the edge of the continental shelf (200 metres) and specifically in water depths greater than 450 metres (the present economic design h i t for fixed structures). Deepwater field developments have so far been concentrated in the Gulf of Mexico and offshore Brazil. While attention and new developments continue there, the deepwater focus is now spreading more worldwide to such areas as the Atlantic Margin, offshore Norway, West Aflica, the South China Sea, offshore Australia, the Falklands, the Mediterranean and even to the deep waters of the land-locked Caspian Sea.
