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Influence of dissolution on frictional properties of carbonate faults

Hadrien Rattez, Fabrizio Disidoro, Jean Sulem, & Emmanouil Veveakis

Published January 13, 2020, SCEC Contribution #10015

Velocity stepping experiments have been performed on a simulated calcite gouge using an annular shear apparatus to investigate the effect of dissolution on the frictional properties of a carbonate fault. The tested material was put in contact with hydrochloric acid at different concentration in order to dissolve the grains. Particle size analysis shows that the small grains tend to disappear due to the chemical reaction, whereas the large grains are not much affected. The dissolution process induces a decrease of the fractal number of the grain size distribution and an increase of the roughness of the particles. The study of the rate-and-state parameters of the gouge, which enables to characterise the ability of the fault to generate earthquakes, shows a weakening due to the dissolution for dry samples and a strengthening for wet samples. This strengthening implies that faults can become less seismogenic after the injection of an acid fluid like in the cases of CO2 storage or acid gas disposal projects in a carbonate reservoir.

Rattez, H., Disidoro, F., Sulem, J., & Veveakis, E. (2020). Influence of dissolution on frictional properties of carbonate faults. Geomechanics for the Energy and the Environment,. doi: 10.31223/osf.io/b8xuh.