Field based stable isotope analysis of COby mid-infrared laser spectroscopy at a pilot site for carbon storage

Wednesday, 17 December 2014: 5:07 PM
H.J. Hansjuerg Jost1,2, Robert Van Geldern3, Martin E Nowak3,4, Martin Zimmer5, Alexandra Szizybalski5, Anssi Myrttinen3 and Johannes Barth3, (1)Thermo Fisher Scientific, Hilterfingen, Switzerland, (2)Thermo Scientific, Bremen, Germany, (3)Friedrich-Alexander University Erlangen-Nürnberg, Department of Geography and Geosciences, Erlangen, Germany, (4)Max Planck Institute for Biogeochemistry, Jena, Germany, (5)GFZ Potsdam, Potsdam, Germany
A newly developed and commercially available isotope ratio laser spectrometer for COanalyses has been tested during a 10-day field monitoring campaign at the Ketzin pilot site for COstorage in northern Germany. The laser instrument is based on tunable laser direct absorption in the mid-infrared. The instrument recorded a continuous 10-day carbon stable isotope data set with 30 minutes resolution directly on-site in a field-based laboratory container during a tracer experiment. To test the instruments performance and accuracy the monitoring campaign was accompanied by daily COsampling for laboratory analyses with isotope ratio mass spectrometry (IRMS). The carbon stable isotope ratios measured by conventional IRMS technique and by the new mid-infrared laser spectrometer agree remarkably well within 2σ analytical precision (<0.3 ‰). This proves the capability of the new mid-infrared direct absorption technique to measure high precision and accurate real-time table isotope data directly in the field. The injected COtracer had a distinct δ13C value that was largely different from the reservoir background value. The laser spectroscopy data revealed a prior to this study unknown, intensive dynamic with fast changing δ13C values. The arrival pattern of the tracer suggest that the observed fluctuations were probably caused by migration along separate and distinct preferential flow paths between injection well and observation well. The new technique might contribute to a better tracing of the migration of the underground COplume and help to ensure the long-term integrity of the reservoir.