Working on new analytical methods

New analytical methods under development

Tuesday 02 Jan 18
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New analytical methods are under development at Danish Hydrocarbon Research and Technology Centre to quantitate the molecular content of crude oil and reservoir fluids.

Oil samples are complex and ‘dirty’, which means that unless precautions are taken, the data quality suffers and lead to uncertain and difficult interpretations. With technological advances in separation science and mass spectrometry, new doors open and with them comes new exciting possibilities. Modern gas chromatography - mass spectrometry (GC-MS) is one of these possibilities, but sample purification is a necessity to get reliable results.

“When implemented, the analyses we are working on will allow us to obtain detailed information on the molecular contenst of crude oil and reservoir fluids. This information is crucial for understanding both bulk physiochemical properties and can tell us about origin, maturation parameters and reservoir connectivity,” says Jonas Sundberg, Postdoc at DHRTC who are working on the new analytical method together with colleague Annette Eva Jensen, Laboratory Technician at DHRTC.

"When implemented, the analyses we are working on will allow us to obtain detailed information on the molecular contenst of crude oil and reservoir fluids."
Jonas Sundberg, Postdoc, DHRTC

Jonas further elaborates: “By mapping various parameters we can follow the compositional changes during core flooding experiments, and aid in the understanding of why certain methods are more efficient than others.”

Laboratory Technician, Annette Eva Jensen is working hard to develop protocols for sample clean-up and fractionation. These protocols will minimize co-elution of unwanted compounds during analysis, and result in more accurate data interpretations and identification of trace components. Quality control measures, are also being initiated to monitor performance over time and identify any instrumental issues in due time, to ensure data integrity.

“The sample molecules are vaporized in a heated inlet, propelled through a long capillary column where they interact with different selectivity and therefore exit at the other end at different times. Here they are exposed to a beam of electrons and effectively charged. An electronic field inside the mass spectrometer guides the charged molecules to a detector. The detector then gives us the molecular weight, and from this information, we can deduce the chemical structure,“ explains Jonas Sundberg as he elaborates on the method behind the analysis and continues:

“For all this to happen the molecules, need to have a suitable vapor pressure. Crude oil consists of up to 90 % small and volatile compounds, which makes it and GC-MS a very good match. However, as it is discriminative towards non-volatiles, complementary techniques must be utilized to fully understand the inner workings of reservoir fluids.”

During the first months of 2018, DHRTC are expanding the laboratory with a liquid chromatography system coupled to an ultrahigh-resolution mass spectrometer. This will allow structural characterization of the polar and high molecular weight compounds, a small but important fraction containing surface-active compounds, which have a big effect on reservoir behavior and recovery processes.

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