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Anticipating sulphur corrosion from crude oil

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Scientists in the US are developing an analysis tool to more accurately predict how sulphur compounds in crude oil might corrode equipment. The research aims to address a major safety issue for fluid handling in the oil industry.

According to a statement from the US Department of Energy, the results of the ongoing research at the Stanford Synchrotron Radiation Lightsource (SSRL) will contribute towards improving oil industry guidelines. Specifically, the study aims to determine which types of sulphur are most important to identify in oil, in order to better predict potential corrosion rates.

“By looking at crude oil with a combination of X-ray spectroscopy techniques, we were able to examine and describe the complex chemistry of the sulphur compounds with high specifity,” said Monica Barney, a materials research engineer at Chevron.

 

Searching for the corrosives

High sulphur concentrations don’t always correlate with high levels of corrosion, and vice versa, making it difficult to predict how corrosive a particular crude oil will be.

“We can measure the concentration of sulphur, but it doesn’t tell you about the reactivity,” Barney, the research leader, explained. “Knowing the type of sulphur in crude oil is critically important for predicting properties related to corrosion.”

The idea behind the research is to use sulphur K-edge X-ray absorption to measure and determine the types of sulphur in crude oils. Barney and his team have developed an approach to examining crude oil using ‘tender X-rays’ – which occupy the middle ground between high-energy and low-energy X-rays.

Tuned to the correct energy, X-rays allowed the researchers to collect detailed information about the sulphur and other chemicals, and observe about the overlapping information generated by similarities in the sulphur compounds.

Essentially, SSRL’s X-ray absorption spectroscopy work allows the scientists to see a precise description of crude oil’s sulphur chemistry.

“This is an example of using state-of-the-art spectroscopy for a real world application,” Graham George, a professor who is involved in the research, explained.

The research is part of a larger collaboration at Chevron that is using several other techniques to understand the chemistry of sulphur in crude oil. The experimental data from several chemical characterisation methods are combined and compared to data from corrosion studies and predictions from computer modelling.