Effect of injected CO2 on geochemical alteration of the Altmark gas reservoir in Germany

• Published in: Environmental earth sciences Vol. 72; no. 9; pp. 3655 - 3662
• Main Authors: Huq, F., Haderlein, S. B., Schröder, C., Marks, M. A. W., Grathwohl, P.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2014; Springer; Springer Nature B.V
• Subjects: Batch reactors; Biogeosciences; Calcite; Carbon dioxide; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Science and Engineering; Exact sciences and technology; Geochemistry; Geologic formations; Geology; Hydrology/Water Resources; Illite; Marine and continental quaternary; Minerals; Original Article; Pollution, environment geology; Reservoirs; Sandstone; Sodium chloride; Spectrum analysis; Storage capacity; Surficial geology; Terrestrial Pollution; Total dissolved solids; Water storage; X-ray diffraction; Central Europe; Europe; Germany; Mineral dissolution; Batch experiments; CO; injection; Sandstone; Mössbauer spectroscopy; atmosphere; experimental studies; illite; reservoir rocks; reservoirs; calcite; feldspar; sulfates; sandstone; formation water; brines; underground storage; partial pressure; Mossbauer spectroscopy; sheet silicates; silicates; framework silicates; clastic rocks; carbon dioxide; anhydrite; liquid phase; dissolution; chlorite; quartz; carbonates; sedimentary rocks; point sources; water-rock interaction; solid phase; clay minerals; alteration; argon
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-014-3276-8

Capturing CO 2 from point sources and storing it in geologic formations is a potential option for allaying the CO 2 level in the atmosphere. In order to evaluate the effect of geological storage of CO 2 on rock-water interaction, batch experiments were performed on sandstone samples taken from the Altmark reservoir, Germany, under in situ conditions of 125 °C and 50 bar CO 2 partial pressure. Two sets of experiments were performed on pulverized sample material placed inside a closed batch reactor in (a) CO 2 saturated and (b) CO 2 free environment for 5, 9 and 14 days. A 3M NaCl brine was used in both cases to mimic the reservoir formation water. For the “CO 2 free” environment, Ar was used as a pressure medium. The sandstone was mainly composed of quartz, feldspars, anhydrite, calcite, illite and chlorite minerals. Chemical analyses of the liquid phase suggested dissolution of both calcite and anhydrite in both cases. However, dissolution of calcite was more pronounced in the presence of CO 2 . In addition, the presence of CO 2 enhanced dissolution of feldspar minerals. Solid phase analysis by X-ray diffraction and Mössbauer spectroscopy did not show any secondary mineral precipitation. Moreover, Mössbauer analysis did not show any evidence of significant changes in redox conditions. Calculations of total dissolved solids’ concentrations indicated that the extent of mineral dissolution was enhanced by a factor of approximately 1.5 during the injection of CO 2 , which might improve the injectivity and storage capacity of the targeted reservoir. The experimental data provide a basis for numerical simulations to evaluate the effect of injected CO 2 on long-term geochemical alteration at reservoir scale.