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- Title
Effect of Fluid Chemistry on the Interfacial Composition, Adhesion, and Frictional Response of Calcite Single Crystals—Implications for Injection‐Induced Seismicity.
- Authors
Diao, Yijue; Espinosa‐Marzal, Rosa M.
- Abstract
While it has been shown that the mechanical properties and the reactivity of carbonate‐bearing rocks may be influenced by the chemical composition of the fluids, little is known about how the fluid composition affects their frictional response. Here, we have used atomic force microscopy to investigate the frictional characteristics of single calcite crystals in calcium carbonate saturated solutions and in two brines, NaCl and CaCl2, at a wide range of geologically relevant concentrations. Surface forces were measured to determine the ion‐specific composition of the confined fluid films and the adhesion between the confining surfaces. The effect of fluid chemistry on calcite's (dynamic) frictional response significantly depends on the normal stress. At low stresses, the confined fluid film lubricates the single‐asperity contact efficiently, resulting in low friction coefficients, especially in the case of NaCl solutions. When the pressure solution of calcite is triggered at sufficiently high stress, a significant reduction of the friction coefficient was observed, and in this case, CaCl2 solutions were shown to promote this frictional weakening more significantly than NaCl. This is the first experimental investigation of the ion‐specific frictional characteristics of calcite at the level of a single‐asperity contact. The presence of infiltrated fluids in carbonate faults may also play a critical role in fault dynamics. Hence, the results of this nanoscale study are extrapolated to carbonate fault friction in the presence of infiltrated fluids, and they contribute to advance our understanding of induced seismicity at geological scale. Key Points: The frictional behavior of calcite was measured in CaCl2 and NaCl solutions by atomic force microscopy, and it was observed to depend on the normal stress, the sliding velocity, and the fluid compositionAt low normal stress, the confined fluid film lubricates the single‐asperity contact efficiently, resulting in low friction, and the friction is lower in NaCl solutionsWhen pressure solution is triggered at sufficiently high normal stresses, a significant weakening of the friction force is observed; this results in a decrease in friction, which is more prominent in CaCl2 brines
- Subjects
CALCITE; MINERAL analysis; CALCITE crystals; SODIUM chlorate; GEOPHYSICS research
- Publication
Journal of Geophysical Research. Solid Earth, 2019, Vol 124, Issue 6, p5607
- ISSN
2169-9313
- Publication type
Article
- DOI
10.1029/2018JB017252