The recent decline in oil price directly affects the investment plans of the oil and gas industry. Due to the slowdown in this sector the allocation of resources in brownfields stands out in the current conjuncture. In today's economically challenging environment, the extension of the platform fatigue design life has become critically important from an economic perspective and because in many cases, platform design life has already been exceeded. An evaluation study was developed targeting the extension of platform design life through the refinement of fatigue analyses.

This work focuses in the improvement of environmental data, like increase of number of wave heading and wave spreading with a better representation of the platform boundary conditions by the implementation of super elements to simulate the soil-structure interaction and using the spectral approach for the fatigue evaluation. These issues were treated individually in order to observe the influence of each one in the analysis results of a representative sample of fixed platforms installed in Brazil.

After the analyses were completed, a comparative study between the results of the refinement performed and the original calculation condition was performed. The results show the level of improvement obtained in the increase of the fatigue design life for the items taken under consideration and their relevance, individually and combined.

It could be concluded that readily achievable improvements in fatigue analysis methodology coupled with refined information, which may already be available, can result in a significant increase in the fatigue design life without the need for high cost inspections. Additionally, through the experience developed in structural re-analysis of existing fixed platforms, other issues like the consideration of local joint flexibility, nonlinear analysis approaches and reliability analysis can also be considered in future jobs to further enhance platform life.

This content is only available via PDF.
You can access this article if you purchase or spend a download.