[Posted on July 24th, 2013 by Bill Stewart]
When it comes to offshore drilling, there are plenty of opportunities to get involved with drilling and exploration and riser analysis is a must. As your company gains contracts and you send rigs out into the deep waters, you need to look at how the risers are selected and used.
Regardless of whether you are using flexible or rigid pipelines, it’s necessary to look at the static and dynamic stress – and this is one of the things that can be done during riser analysis. This ensures you have thought of everything, including load capacities. As you do this analysis, it will allow you to choose the most effective risers for the job.
Many offshore drilling companies have begun using flexible risers as the default riser style because it can deal with horizontal and vertical forces. While this is true, it is not always going to be the best when it comes to fatigue – and this is another instance where riser analysis can show you what is truly going on so you can make an accurate assessment as to the risers you obtain as well as the design that you put into place.
Where you will be drilling matters. The water in one part of the world is going to be entirely different than the water in another part of the world. Waves, temperature, salinity and various other factors must be calculated. You will need a vortex-induced vibration assessment to ensure you have captured every possible scenario.
A sound structure is of the utmost importance. You will likely have a plan in place should you have an emergency disconnect of a riser, however you want to prevent this scenario from happening to begin with – and this is why it is of the utmost importance to spend the time ahead of time to get the riser analysis done.
There are several ways to achieve this analysis – and it shouldn’t be a choice as to which you should do – you should be doing both simply to run your numbers in multiple ways. The first is to use software to run the calculations and scenarios. OrcaFlex is a popular software program to run scenarios when you are offshore drilling. It will do a lot of assessment and analysis on your behalf. The second is to work with a consulting group that will run a variety of scenarios by you as well as look at the design of your rig with risers to ensure structural integrity is maintained throughout the scenarios.
Once you get out into the deep waters, you are a long way away from assistance of any sort. You will have communications, but it can take a while for someone to get out to you. If you lose structural integrity, you lose everything – and that’s not something you should deal with. Riser analysis can be the way to double check all of your calculations before heading out.