Origin and heterogeneity of pore sizes in the Mount Simon Sandstone and Eau Claire Formation: Implications for multiphase fluid flow

Journal Article · Fri Jan 01 00:00:00 EST 2016 · Geosphere

DOI:https://doi.org/10.1130/ges01245.1· OSTI ID:1333930

Mozley, Peter S. ^[1]; Heath, Jason E. ^[2]; Dewers, Thomas A. ^[2]; Bauer, Stephen J. ^[2]

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1. New Mexico Institute of Mining and Technology, Socorro, NM (United States)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

The Mount Simon Sandstone and Eau Claire Formation represent a principal reservoir - caprock system for wastewater disposal, geologic CO₂ storage, and compressed air energy storage (CAES) in the Midwestern United States. Of primary concern to site performance is heterogeneity in flow properties that could lead to non-ideal injectivity and distribution of injected fluids (e.g., poor sweep efficiency). Using core samples from the Dallas Center Structure, Iowa, we investigate pore structure that governs flow properties of major lithofacies of these formations. Methods include gas porosimetry and permeametry, mercury intrusion porosimetry, thin section petrography, and X-ray diffraction. The lithofacies exhibit highly variable intra- and inter-informational distributions of pore throat and body sizes. Based on pore-throat size, samples fall into four distinct groups. Micropore-throat dominated samples are from the Eau Claire Formation, whereas the macropore-, mesopore-, and uniform-dominated samples are from the Mount Simon Sandstone. Complex paragenesis governs the high degree of pore and pore-throat size heterogeneity, due to an interplay of precipitation, non-uniform compaction, and later dissolution of cements. Furthermore, the cement dissolution event probably accounts for much of the current porosity in the unit. The unusually heterogeneous nature of the pore networks in the Mount Simon Sandstone indicates that there is a greater-than-normal opportunity for reservoir capillary trapping of non-wetting fluids — as quantified by CO₂ and air column heights — which should be taken into account when assessing the potential of the reservoir-caprock system for CO₂ storage and CAES.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Frontiers of Subsurface Energy Security (CFSES)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC04-94AL85000; SC0001114
• OSTI ID: 1333930
• Report Number(s): SAND-2015-6758J; 598878
• Journal Information: Geosphere, Vol. 12, Issue 4; ISSN 1553-040X
• Publisher: Geological Society of America
• Country of Publication: United States
• Language: English

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58 GEOSCIENCES