NETL LabNotes

NETL Validates Innovative Spectrometry Technique

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Graphic representation of in situ measurements of calcium carbonate dissolution under rising CO2 pressure using underwater laser-induced breakdown spectroscopy. Image used as the front cover for the Journal of Analytical Atomic Spectrometry’s July 2016 issue.

An article highlighting NETL’s research into the use of laser spectrometry to collect data vital to ensuring the efficacy and safety of geologic carbon storage sites was recently featured in the July edition of the Journal on Analytical Atomic Spectrometry (JAAS). JAAS is a highly regarded, peer-reviewed research publication that focuses on fundamentals, instrumentation, and methods in the determination, speciation, and isotopic analysis of trace elements.

The NETL research team’s article, titled “In situ measurements of calcium carbonate dissolution under rising CO2 pressure using underwater laser-induced breakdown spectroscopy,” was co-authored by Christian L. Goueguel, Jinesh C. Jain, Dustin L. McIntyre, Cantwell G. Carson, and Harry M. Edenborn. The study focused on the application of underwater laser-induced breakdown spectroscopy for rapid in situ measurements of calcium carbonate dissolution as a function of CO2 pressure.

While performing carbon storage in geologic formations, it is vital to understand the way that the reservoir rocks and the cap rocks that seal the reservoirs interact with the CO2. These interactions will impact the amount of CO2 that can effectively be trapped within the minerals and native fluids of the reservoir, determining both quantity and the security of long-term storage. Limestone, for instance, is an extremely common buffering rock that becomes reactive when exposed to CO2 and alters in such a way that its porosity and permeability can increase and create a potential pathway for the CO2 to leak to the surface.

The geophysics research team, understanding the importance of predicting the behavior of reservoir rocks over long durations, sought to develop a methodology that could accurately simulate field testing experiments within a laboratory environment—thereby increasing the cost-effectiveness of the research. A hurdle facing most laboratory attempts to execute experiments involving CO2 in high-pressure environments is the difficulty in sampling the fluid during the experiment. To counter this challenge, the NETL team tested the use of laser-induced breakdown spectroscopy (LIBS). LIBS is a powerful analytical technique that allows researchers to determine trace-element distribution and concentrations with parts per million resolution, high sensitivity, and low detection limit.

The research team concluded that the use of underwater LIBS was an effective method of acquiring direct in situ measurements of calcium carbonate dissolution when paired with elevated CO2 levels. While not conclusive, the team believes that underwater LIBS has the potential to advance geologic carbon storage research by providing a practical means of acquiring real-time data on elements released during carbonate dissolution resulting from the degradation of cement seals.

Data collected by the NETL research team, and from future research performed using the techniques they validated, are crucial to geological carbon storage efforts. The ingenuity demonstrated by the NETL researchers involved in this project is a key component to advancing NETL’s mission of discovering, integrating, and maturing technology solutions to enhance the nation’s energy foundation and protect the environment for future generations.