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Title: Mineral dissolution and precipitation during CO2 injection at the Frio-I Brine Pilot: Geochemical modeling and uncertainty analysis

During the Frio-I Brine Pilot CO2 injection experiment in 2004, distinct geochemical changes in response to the injection of 1600 tons of CO2 were recorded in samples collected from the monitoring well. Previous geochemical modeling studies have considered dissolution of calcite and iron oxyhydroxides, or release of adsorbed iron, as the most likely sources of the increased ion concentrations. We explore in this modeling study possible alternative sources of the increasing calcium and iron, based on the data from the detailed petrographic characterization of the Upper Frio Formation “C”. Particularly, we evaluate whether dissolution of pyrite and oligoclase (anorthite component) can account for the observed geochemical changes. Due to kinetic limitations, dissolution of pyrite and anorthite cannot account for the increased iron and calcium concentrations on the time scale of the field test (10 days). However, dissolution of these minerals is contributing to carbonate and clay mineral precipitation on the longer time scales (1000 years). The one-dimensional reactive transport model predicts carbonate minerals, dolomite and ankerite, as well as clay minerals kaolinite, nontronite and montmorillonite, will precipitate in the Frio Formation “C” sandstone as the system progresses towards chemical equilibrium during a 1000-year period. Cumulative uncertainties associated with usingmore » different thermodynamic databases, activity correction models (Pitzer vs. B-dot), and extrapolating to reservoir temperature, are manifested in the difference in the predicted mineral phases. Furthermore, these models are consistent with regards to the total volume of mineral precipitation and porosity values which are predicted to within 0.002%.« less
Authors:
 [1] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
OSTI Identifier:
1238583
Report Number(s):
SAND--2015-7786J
Journal ID: ISSN 1750-5836; PII: S1750583615301377
Grant/Contract Number:
AC04-94AL85000; SC000114
Type:
Accepted Manuscript
Journal Name:
International Journal of Greenhouse Gas Control
Additional Journal Information:
Journal Volume: 44; Journal ID: ISSN 1750-5836
Publisher:
Elsevier
Research Org:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
CO₂ geologic storage; saline aquifers; mineral trapping; dissolution; pyrite; calcite