Many platforms in the Danish oil fields in the North Sea were built in the early 1980s with a typical design life from 20-30 years. Now, up to 40 years and a number of repairs and modifications later, we investigate the state of the platforms and assess the measures needed to maintain these as fit for continued production.
Offshore structures are constantly experiencing the impact of the environment including wind, waves and salt. For the offshore steel structures, this causes fatigue reducing the strength and increasing the risk of failure. Primarily using modal analysis, we are investigating the behavior and fatigue level of the installations with the aim to provide insights on the actual remaining strength.
With the recent observation of a breaking wave under the Tyra platform, a wave form previously considered not to occur at such offshore locations, highlights the need for further knowledge on wave patterns and frequencies. Breaking waves have a completely different and more violent force than ordinary waves, and so we are investigating whether previous wave impact calculations have been sufficiently conservative in terms of securing platforms and personnel.
An advanced risk model including value of information evaluations is being developed which will combine the knowledge developed on structural fatigue and wave loading. The model provides an assessment of the failure risk supporting the operator to make risk based decisions on the structural health and evaluate need for repair and inspections.
By securing production in this way, we contribute to continuing one of the most energy-efficient oil production in the world. Denmark is a world leader when it comes to extracting oil with low energy consumption and research into the structural integrity of the platforms is a significant contribution to keep production going.
Placement of possible new platforms
Alongside the work on the existing platforms, we have also done research on how advanced interpretation of shallow seismic surveys can assist in evaluating where to place new structures based on expected strength of the seabed.
The research is carried out in close collaboration with TotalEnergies, who as an operator in DUC is responsible for the maintenance of the platforms in the Danish fields. The goals of the program are defined in collaboration with TotalEnergies, which has identified the most obvious problems to tackle, after which our researchers come up with solutions and develop prototypes. In this way, the distance from idea to applied research becomes as low as possible.