Experimental observation of permeability changes in dolomite at CO 2 sequestration conditions

Benjamin M. Tutolo, Andrew J. Luhmann, Xiang Zhao Kong, Martin O. Saar, William E. Seyfried

Research output: Contribution to journalArticle

38 Scopus citations

Abstract

Injection of cool CO2 into geothermally warm carbonate reservoirs for storage or geothermal energy production may lower near-well temperature and lead to mass transfer along flow paths leading away from the well. To investigate this process, a dolomite core was subjected to a 650 h, high pressure, CO2 saturated, flow-through experiment. Permeability increased from 10-15.9 to 10-15.2 m2 over the initial 216 h at 21 C, decreased to 10-16.2 m2 over 289 h at 50 C, largely due to thermally driven CO2 exsolution, and reached a final value of 10-16.4 m2 after 145 h at 100 C due to continued exsolution and the onset of dolomite precipitation. Theoretical calculations show that CO2 exsolution results in a maximum pore space CO2 saturation of 0.5, and steady state relative permeabilities of CO2 and water on the order of 0.0065 and 0.1, respectively. Post-experiment imagery reveals matrix dissolution at low temperatures, and subsequent filling-in of flow passages at elevated temperature. Geochemical calculations indicate that reservoir fluids subjected to a thermal gradient may exsolve and precipitate up to 200 cm3 CO2 and 1.5 cm 3 dolomite per kg of water, respectively, resulting in substantial porosity and permeability redistribution.

Original languageEnglish (US)
Pages (from-to)2445-2452
Number of pages8
JournalEnvironmental Science and Technology
Volume48
Issue number4
DOIs
StatePublished - Feb 18 2014

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