Surface Gas Geochemistry above the Natural CO sub(2) Reservoir of Montmiral (Drome, France), Source Tracking and Gas Exchange between the Soil, Biosphere and Atmosphere

• Published in: Oil & gas science and technology 2010-08, Vol.65 (4), p.635-652
• Main Authors: Gal, F, Le Pierres, K, Brach, M, Braibant, G, Beny, C, Battani, A, Tocque, E, Benoit, Y, Jeandel, E, Pokryszka, Z
• Format: Article
• Language: English
• Subjects: Air pollution; Atmospheres; Carbon capture and storage; Carbon dioxide; Fluxes; Geochemistry; Natural gas; Soil (material); Underground storage
• ISSN: 1294-4475
• DOI: 10.2516/ogst/2009068

One of the options considered to mitigate greenhouse gas concentrations in the atmosphere is underground storage of CO sub(2). There is a strong need for enhancing and developing methods that would help throughout the duration life of such underground storage, to ensure the safety and able to monitor the evolution of the injected CO sub(2) plume. Among these, geochemical methods can play an important role. Here, we describe results acquired under the research programme "Geocarbone-Monitoring", partially funded by the French National Research Agency, on the Montmiral natural analogue in South-Eastern France. Other results obtained under the same research programme in the French Massif Central are reported elsewhere in this volume. Spot sampling methods allowing a great geographical coverage and continuous measurements on selected points were undertaken in 2006 and 2007, in order to determine soil gas concentrations and fluxes as well as carbon isotope ratio determinations. One important result is that without any evidence of deep CO sub(2) leakage, both CO sub(2) concentrations and fluxes appear to be higher than can be explained only by biological activities. Further investigations are thus needed to understand the gas evolution better throughout the year.Original Abstract: Une des options envisagees pour reguler les concentrations de gaz a effet de serre dans l'atmosphere est le stockage souterrain du CO sub(2). Dans ce domaine existe un fort besoin de renforcer et de developper des methodes susceptibles d'etre utilisees tout au long de la duree de vie de ces stockages souterrains, afin de s'assurer de leur securite et de pouvoir suivre l'evolution du panache de CO sub(2) injecte. Parmi elles, les methodes geochimiques peuvent jouer un role important. Nous decrivons ici les resultats acquis dans le cadre du programme de recherche "Geocarbone-Monitoring" finance en partie par l'Agence Nationale de la Recherche sur l'analogue naturel de Montmiral dans le Sud-Est de la France. D'autres resultats obtenus dans le cadre de ce meme programme de recherche sont rapportes dans un autre article present dans ce volume. Des methodes d'echantillonnage ponctuelles permettant une grande couverture geographique et des mesures en continu sur certains points selectionnes ont ete entreprises en 2006 et 2007, afin de permettre la determination des concentrations en gaz du sol et des flux, ainsi que des determinations des rapports isotopiques du carbone. Sans aucune preuve d'u