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Dissolution and precipitation dynamics during dedolomitization
Author(s) -
Edery Yaniv,
Scher Harvey,
Berkowitz Brian
Publication year - 2011
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2011wr010551
Subject(s) - dissolution , precipitation , dolomite , mineralogy , geology , chemistry , meteorology , physics
We simulate the processes of dedolomitization and calcium carbonate precipitation using particle tracking. The study is stimulated by the results of a laboratory experiment that examined reactive transport of injected CaCl 2 /HCl, into a column of sucrosic dolomite particles, with a constant flow field. The injected fluid supplies Ca 2+ and H + . Dedolomitization is a protonation reaction yielding carbonic acid; a subsequent deprotonation reaction yields , and reaction with the abundant Ca 2+ forms the precipitate CaCO 3 . The dedolomitization and precipitation processes involve multistep, multispecies chemical reactions, with both irreversible and reversible stages. The particle tracking is governed by spatial and temporal distributions within a continuous time random walk framework. This accounts for the effects of disorder of heterogeneous media (leading to non‐Fickian transport) and includes the option of treating purely advective‐dispersive (Fickian) transport. The dynamics of dedolomitization are examined for different flow conditions and reaction rates. The fluctuations in the local velocity distributions, due to porosity changes, create conditions for positive feedbacks leading to development of preferential pathways, large‐scale nonlinearity, and precipitation banding. These features have been observed in the laboratory experiments and are now accounted for by the simulation results at similar time frames, velocities, and pH levels.