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Fracture sealing by mineral precipitation: The role of small‐scale mineral heterogeneity
Author(s) -
Jones Trevor A.,
Detwiler Russell L.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl069598
Subject(s) - precipitation , geology , fracture (geology) , mineral , mineralogy , permeability (electromagnetism) , soil science , materials science , geotechnical engineering , chemistry , metallurgy , biochemistry , physics , membrane , meteorology
Fractures are often leakage pathways for fluid in low‐permeability rocks that otherwise act as geologic barriers in the subsurface. Flow of fluids in chemical disequilibrium with fracture surfaces can lead to mineral precipitation and fracture sealing. To directly evaluate the role of small‐scale mineral heterogeneity on mineral precipitation, we measured CaCO 3 precipitation in a transparent analog fracture that included randomly distributed small‐scale regions of CaCO 3 on one of the borosilicate surfaces. Steady flow of a well‐mixed CaCl 2 ‐NaHCO 3 solution ( log ( ΩCaC O 3) = 1.44) resulted in significant mineral precipitation during the 82 day experiment. Localized mineral precipitation reduced flow within regions of the fracture, but small‐scale reaction‐site heterogeneity allowed preferential flow to persist through pathways that contained 82% less area of CaCO 3 regions than the fracture‐scale average. This resulted in a significant reduction in measured precipitation rate; excluding these effects results in more than an order‐of‐magnitude underestimation of fracture sealing timescales.