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Permeability Evolution of a Cemented Volcanic Ash During Carbonation and CO 2 Depressurization
Author(s) -
Clark A. C.,
MacFarlane J.,
Vanorio T.
Publication year - 2018
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2018jb015810
Subject(s) - carbonation , permeability (electromagnetism) , lime , volcanic ash , hydrothermal circulation , volcano , cement , pore water pressure , geology , carbon dioxide , geotechnical engineering , petroleum engineering , geochemistry , materials science , composite material , chemistry , biochemistry , organic chemistry , membrane , seismology , paleontology
The presence of calcium‐cemented ash beds serving as caprocks in hydrothermal systems calls for the examination of any chemo‐mechanical processes that may undermine or enhance their sealing capacity. Understanding these processes provides new information regarding how to model time‐dependent observations associated with seismicity and/or deformation in volcanic areas. In addition, since these ash beds are inherently similar to ash‐based concrete, a bridge of knowledge can be built across disciplines in the earth sciences and engineering. This paper investigates how the permeability of a volcanic ash cemented with hydrated lime changes upon exposure to carbon dioxide (CO 2 ) in humid and hydrous conditions relevant to natural or human‐driven processes such as those found in hydrothermal settings or near wellbores used for secondary oil recovery, CO 2 plume geothermal energy, or carbon storage. We characterized samples by their permeability during carbonation and subsequent changes in pore pressure and confining pressure. Products from the reaction of CO 2 with the cemented ash matrix reduced permeability and entrapped fluids. The regions within samples permeated with unreacted CO 2 were susceptible to fracturing upon rapid depressurization, but only when the effective stress state was sufficiently low. Altogether, the results indicate that lime‐cemented volcanic ash beds are particularly suited to act as flow barriers to CO 2 ‐rich fluids.