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The Cambrian Mount Simon Sandstone is the major target reservoir for ongoing geologic carbon dioxide (CO 2) sequestration demonstrations throughout the midwest United States. The potential CO 2 reservoir capacity, reactivity, and ultimate fate of injected CO 2 depend on textural and compositional properties determined by depositional and diagenetic histories that vary vertically and laterally across the formation. Effective and efficient prediction and use of the available pore space requires detailed knowledge of the depositional and diagenetic textures and mineralogy, how these variables control the petrophysical character of the reservoir, and how they vary spatially. Here, we summarize the reservoir characteristics of the Mount Simon Sandstone based on examination of geophysical logs, cores, cuttings, and analysis of more than 150 thin sections. These samples represent different parts of the formation and depth ranges of more than 9000 ft (>2743 m) across the Illinois Basin and surrounding areas. This work demonstrates that overall reservoir quality and, specifically, porosity do not exhibit a simple relationship with depth, but vary both laterally and with depth because of changes in the primary depositional facies, framework composition (i.e., feldspar concentration), and diverse diagenetic modifications. Diagenetic processes that have been significant in modifying the reservoir include formation of iron oxide grain coatings, chemical compaction, feldspar precipitation and dissolution, multiple generations of quartz overgrowth cementation, clay mineral precipitation, and iron oxide cementation. These variables provide important inputs for calculating CO 2 capacity potential, modeling reactivity, and are also an important baseline for comparisons after CO 2 injection.
Brenda B. Bowen is an assistant professor in the Department of Earth and Atmospheric Sciences at Purdue University. She received her B.S. and M.S. degrees in earth science from the University of California, Santa Cruz, and her Ph.D. in geology from the University of Utah in 2005. Her research is focused on understanding depositional and diagenetic processes that influence reservoir characteristics and paleoenvironmental records.
Raul I. Ochoa is an M.S. student at Purdue University, studying reservoir characterization and diagenetic analysis of the Mount Simon Sandstone in the Illinois Basin related to geologic CO 2 sequestration. He received his B.S. degree from the University of Texas at El Paso in geology in 2008.
Nathan D. Wilkens is a postdoctoral research associate in the Department of Earth and Atmospheric Sciences at Purdue University. He earned his B.S. degree in geology in 2003 and a Ph.D. in geological sciences from Arizona State University in 2008. His research emphasis has been on depositional environments and paleoecology of terrestrial environments.
James Brophy is an associate professor of igneous petrology at Indiana University. His research specializes in the origin and differentiation of magma and uses a combination of field, analytical, theoretical, and experimental approaches. An important component of his work is the characterization of rock texture, mineralogy, and mineral composition through the application of petrographic and electron microprobe analytical techniques.
Thomas R. Lovell is a Ph.D. student at Purdue University, studying interactions between provenance and overall reservoir development in the Mount Simon Sandstone. He completed his M.S. thesis research at the University of Alabama while studying detrital zircon geochronology of an Early Jurassic reservoir in the Gulf of Mexico and his B.S. degree at the University of Tennessee-Chattanooga.
Nick Fischietto received a B.S. degree from Allegheny College with a major in geology and an M.S. degree from Purdue University in geologic sciences, with a focus on clastic sedimentology. He is now working in the oil and gas industry in Oklahoma City.
Cristian R. Medina is a reservoir geologist at the Indiana Geological Survey at Indiana University, Bloomington. He earned his B.S. degree in geology at the University of Chile in 2001 and his M.S. degree in hydrogeology at Indiana University, Bloomington, in 2007. He currently works for Midwest Regional Carbon Sequestration Partnership on the subsurface characterization of Cambrian sandstones.
John A. Rupp is a senior research scientist in the Subsurface Geology Section of the Indiana Geological Survey and associate director for science at the Center for Research on Energy and the Environment at Indiana University. He received his M.S. degree from Eastern Washington University in 1980, with emphasis on porphyry molybdenum deposits. Before joining the survey, he worked for Exxon Production Co. U.S.A. and for Salisbury and Dietz, Inc.