Geochemistry of CO₂ Sequestration in the Jurassic Navajo Sandstone, Colorado Plateau, Utah

Authors

W. T. Parry, University of Utah
Craig B. Forster, University of Utah
James P. Evans, Utah State UniversityFollow
Brenda Beitler Bowen, University of Utah
Marjorie A. Chan, University of Utah

Document Type

Article

Journal/Book Title/Conference

Environmental Geosciences

Volume

14

Issue

2

Publisher

American Association of Petroleum Geologists

Publication Date

2007

First Page

91

Last Page

109

Abstract

The Jurassic Navajo Sandstone on the Colorado Plateau of Utah may be considered for sequestration of CO₂, because it is thick, widely distributed, has a high porosity and permeability, is typically horizontal to gently folded, is favorably located with respect to seal strata, and underlies many large point sources of CO₂. However, faulting common on the Colorado Plateau may provide pathways for leakage of the CO₂ similar to present-day geysers and CO₂-charged springs. Natural groundwater present in the Navajo Sandstone includes a range of low-salinity, moderate-salinity with high bicarbonate, and high-salinity waters. Higher salinity waters may have moved from deeper strata under artesian pressures or originated from solution of evaporite in pre-Jurassic rocks. These characteristics make the Navajo Sandstone an excellent analog for examining the geochemistry of CO₂ injection into deep saline aquifers. The storativity of CO₂ in solution is a function of the solubility of CO₂ in these waters, which is dependent on salinity, temperature, and pressure. Geochemical modeling shows that the coolest, least saline water can contain the most CO₂ in solution. Dissolving CO₂ in the water lowers the pH, so that no minerals precipitate, and the Navajo Sandstone contains only small amounts of mineral that may consume the H⁺. The reaction of the acidic water produced by dissolving CO₂ with K-feldspar and minor clays and calcite in the sandstone throughout 500 yr consumes little H⁺ and produces only small amounts of product minerals. The Navajo Sandstone likely would not store significant CO₂ as mineral precipitate, and thus, stored volumes of CO₂ would be limited by its solubility in the in-situ water and storage as free CO₂ in pore space.

Comments

Originally published by the American Association of Petroleum Geologists. Abstract available through remote link. Subscription required to access article fulltext.

Recommended Citation

Parry, W. T., Forster, C. B., Evans, J. P., Beitler, B., and Chan, M. A., 2007, Geochemistry of CO₂ sequestration in the Jurassic Navajo Sandstone, Colorado Plateau, Utah, Environmental Geosciences, 14, 91-109.