New Tool Predicts Effects of Inclement Weather on Offshore Equipment

For offshore operations to cope with more extreme weather conditions, DNV has developed the new Riser Production Line software suite. Its automated and efficient calculations dramatically reduces the analysis time of how heavy weather and operating conditions will strain installations such as risers, moorings and umbilicals.

As oil exploration activities move rapidly into deeper waters, harsher environments and more remote locations, where not only production but also drilling activities become critical applications, existing technologies will reach their limits.

"Whilst important new technologies are being developed, DNV has focused on achieving a more cost-effective solution by refining the calculation methodologies and loading conditions. This in order to reduce the design uncertainties," explains Celso Raposo, DNV's segment director for Deepwater and Ultra-deepwater Field Development.

The traditional risers' software package produces a remarkable amount of data to be compiled by the analysts. It requires a tremendous effort to interpret the results and draw conclusions. However, DNV's new Riser Production Line allows automated and efficient calculations, thus reducing the total analysis time to a fraction of the usual.

"The tool enables us to post-process the analysis results from time-domain simulations of dynamic marine systems more efficiently. The core analysis programs are Riflex and Flexcom. The Riser Production Line reads data from result databases and analyses these using common post-processing tools," says Nils Sødhal, DNV's project development manager.

The main features of the Riser Production Line are:

--Time series analyses, including extreme value predictions

--Plotting of time series and response spectra

--Filtering and time-series manipulations, including common transformations

--Riser capacity checks according to different standards

--Riser fatigue life predictions based on Rain Flow Cycle Counting (RFCC)

Parts of the Riser Production Line have also been implemented in DeepC software, which is time domain coupled analysis software for risers and moorings. DeepC has been developed and marketed by DNV, and its analysis engines are SIMO and RIFLEX, which are owned, developed and maintained by MARINTEK.