Since the group ranks as one of the world’s largest oil exporters, it is constantly seeking to maximise the value of its sales portfolio.
This requires extensive knowledge of the quality of an increasing variety of crudes, and the ability to overcome potential refining problems as they arise.
Some years ago, an initiative was launched for systematically building up research and development expertise to cope with these aspects.
The aims were to develop the necessary understanding of quality-related factors which could reduce the attractiveness of certain crudes to StatoilHydro customers, and to have solutions available for their safe processing.
This work has focused mainly on crudes with a high content of naphthenic acids. These not only cause production problems, but are also corrosive and can severely damage refinery equipment if no precautions have been taken.
Naphthenic acid corrosion is difficult to predict, however, because it depends on several factors, such as metallurgy, flow, temperature and fluid chemistry.
A rig was therefore constructed in the laboratory at StatoilHydro's research centre in Trondheim to study the corrosion potential of different fluids under varying operating conditions.
Thanks to its breakthrough in understanding the fundamental mechanism of calcium naphthenate formation, the group already has the analytical tools needed to correlate corrosion data with specific types of naphthenic acid.
The next step is to find ways of safely processing the increasing range of acidic crudes.
The ultimate solution is to remove the acids prior to refining, of course, and StatoilHydro’s researchers are getting close to this goal.
Naphthenic acid removal (NAR), a proprietary process developed by the group, can selectively remove these acids under mild conditions using catalytic hydrotreatment. Hydrogen consumption is low and no yield loss occurs.
Extensive pilot tests have now been completed at the research centre, and the process is ready for commercialisation.
