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The AAPG/Datapages Combined Publications Database

Environmental Geosciences (DEG)

Abstract

Environmental Geosciences, V. 23, No. 2 (June 2016), P. 81-93.

Copyright ©2016. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

DOI: 10.1306/eg.09031515006

Chemical effects of carbon dioxide sequestration in the Upper Morrow Sandstone in the Farnsworth, Texas, hydrocarbon unit

Bulbul Ahmmed,1 Martin S. Appold,2 Tianguang Fan,3 Brian J. O. L. McPherson,4 Reid B. Grigg,5 and Mark D. White6

1Department of Geological Sciences, 101 Geological Sciences Building, University of Missouri, Columbia, Missouri 65211; [email protected]
2Department of Geological Sciences, 101 Geological Sciences Building, University of Missouri, Columbia, Missouri 65211; [email protected]
3Petroleum Recovery Research Center, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, New Mexico 87801; [email protected]
4Department of Civil and Environmental Engineering, University of Utah, 110 Central Campus Drive, Suite 2000, Salt Lake City, Utah 84112; [email protected]
5Petroleum Recovery Research Center, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, New Mexico 87801; [email protected]
6Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MSIN K9-33, Richland, Washington 99352; [email protected]

ABSTRACT

Numerical geochemical modeling was used to study the effects on pore-water composition and mineralogy from carbon dioxide (CO2) injection into the Pennsylvanian Morrow B Sandstone in the Farnsworth Unit in northern Texas to evaluate its potential for long-term CO2 sequestration. Speciation modeling showed the present Morrow B formation water to be supersaturated with respect to an assemblage of zeolite, clay, carbonate, mica, and aluminum hydroxide minerals and quartz. The principal accessory minerals in the Morrow B, feldspars and chlorite, were predicted to dissolve. A reaction-path model in which CO2 was progressively added up to its solubility limit into the Morrow B formation water showed a decrease in pH from its initial value of 7 to approximately 4.1 to 4.2, accompanied by the precipitation of small amounts of quartz, diaspore, and witherite. As the resultant CO2-charged fluid reacted with more of the Morrow B mineral matrix, the model predicted a rise in pH, reaching a maximum of 5.1 to 5.2 at a water–rock ratio of 10:1. At a higher water–rock ratio of 100:1, the pH rose to only 4.6 to 4.7. Diaspore, quartz, and nontronite precipitated consistently regardless of the water–rock ratio, but the carbonate minerals siderite, witherite, dolomite, and calcite precipitated at higher pH values only. As a result, CO2 sequestration by mineral trapping was predicted to be important only at low water–rock ratios, accounting for a maximum of 2% of the added CO2 at the lowest water–rock ratio investigated of 10:1, which corresponds to a small porosity increase of approximately 0.14% to 0.15%.

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