『Abstract
A series of kinetic experiments has been carried out to investigate
the rates of dissolution (release of Al and Si) of common sandstone
minerals in response to acidification of pore waters (pH = 3),
using an experimental procedure designed to maximise the proportion
of solid to fluid, and to minimise possible damage from agitation.
The results have then been compared with those from experiments
using disaggregated sandstones from two North Sea reservoirs.
Experiments were carried out at 25℃ and 80℃ and in 0.01, 0.1 and
1 M NaCl solutions, with a pH of 3. Hydrochloric acid was used
as the source of acidity and rate constants were determined based
on both release of Al and Si. Mineral dissolution rates were closely
comparable to literature values, despite the difference experimental
technique, except in the case of smectite where particle aggregation
appears to have inhibited reaction. The dissolution rates calculated
for reservoir sandstones based on their modal mineralogy and surface
areas agree with within a factor of 2 with the measured vales.
Based on the reaction rates measured here, reservoir rocks rich
in feldspar, illite and/or smectite are likely to react most rapidly
with acidified pore waters.』
1. Introduction
2. Starting materials
2.1. Minerals
2.2. Reservoir rocks
2.2.1. Beryl
2.2.2. Huldra
3. Dissolution experiments
4. Mineral hydrolysis reactions
4.1. Smectite (STx-1)
4.2. Kaolinite (KGa 1-b)
4.3. Illite (IMt-1)
4.4. Albite (HR-108)
4.5. Labradorite
5. Reaction rate calculations
6. Results
6.1. Activation energies
7. SEM observations
8. Interpretation of mineral dissolution data
8.1. Smectite
8.2. Kaolinite
8.3. Illite
8.4. Albite
8.5. Labradorite
9. Chemical affinity effects
10. Interpretation of sediment dissolution data
10.1. Hudra
10.2. Beryl
11. Implications for CO2 sequestration in
silicate reservoirs
11.1. Effect of salinity on reaction rate
11.2. Clay vs. feldspar reaction rates
11.3. Aluminosilicate vs. carbonate reaction rates
12. Conclusions
Acknowledgements
References