New multiphase flow modelling software available
Feature Articles, Nov  27  2009 (Digital Energy Journal)

- A new multiphase flow modelling software is available on general release from Kongsberg, building on an estimated $20 m of research funded by Total and ConocoPhillips at the SINTEF research organisation in Trondheim.

The software is already being used by Total and ConocoPhillips, but is now released for commercial use.

The software was designed to model typical subsea flow lines, typically running at a long distance along the seabed and then suddenly turns to rise to the surface, with several kilometres of vertical height.

Kongsberg software- modelling complex flows in long subsea flow lines

Having good multiphase flow models is very important in avoiding slugs (e.g. large volumes of liquid in the gas flowline) which can come up to the platform and cause enormous problems.

If you know what kind of conditions can cause slugs, you can try to tweak the flowrates and pressures to avoid them.

The software calculates the dynamic fluid flow in three dimensions, and can simulate and visualise waves, slugs, droplets and bubbles.

It can also help you manage the flow to try to reduce hydrates, which can solidify out of the liquid and gas flowing through the pipe and block it.

Total and ConocoPhillips invested in the new technology because they were struggling to adequately model multiphase flow in these complex conditions with the technology available, says Chris Ruigrok, head of sales, multiphase flow solutions, with Kongsberg Oil and Gas Technologies. "It is difficult to accurately simulate multiphase flow in the risers with current tooling."

The system calculates in more detail than the competitors, Mr Ruigrok claims. "The main aim is to predict liquid hold up more accurately," he says.

The project combines together detailed calculations of oil and gas flow based on the fundamental physical and chemical properties, with real experimental data from the SINTEF Multiphase Flow Laboratory, where there is a 12 inch diameter flowline setup with a 70 m vertical riser.

20 people have been working full time on developing it since 2002. "Experimental data is very expensive but it's also very important," says Mr Ruigrok.

Kongsberg has established a new business unit called Multiphase Flow Solutions to industrialise the technology, and look for ways to combine it with other product offerings, for example its K-Spice software which can model oil and gas process plant and control systems.

Setting the software up is fairly simple - you type in the shape of the pipeline (in terms of x, y, z co-ordinates at different lengths along it), you type in the data about the pipe and its contents - diameter, pressure, fluid temperature at start, outer temperature, heat transfer co-efficient, description of the fluid and start (ratio of gas, oil and water) and estimate of pressure in the well. The simulator then works out everything else.

If you want to see if you can reduce slugging with a choke in the pipeline, you can see how well this will work.

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