Numerical modeling of non-isothermal quartz dissolution/precipitation in a coupled fracture–matrix system

• Published in: Geothermics Vol. 34; no. 4; pp. 411 - 439
• Main Authors: Kumar, G. Suresh, Ghassemi, Ahmad
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2005; Elsevier Science
• Subjects: Dual porosity; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Fracture aperture; Geothermics; Quartz dissolution/precipitation; Reactive solute transport; Silica; Thermal transport; Thermal transport; Dual porosity; Reactive solute transport; Silica; Fracture aperture; Quartz dissolution/precipitation; diffusion; solutes; porosity; silica; dissolution; reservoirs; quartz; transport; velocity; inlets; precipitation; numerical models; silicates; framework silicates; thermal conductivity; dispersion; fractures
• ISSN: 0375-6505; 1879-3576
• DOI: 10.1016/j.geothermics.2005.04.003

A numerical model is developed to simulate the combined effect of thermal and reactive solute transport in a coupled fracture–matrix system using dual porosity concepts. The model includes solute dispersion in the fracture, lateral diffusion-limited transport of solutes from the fracture into the reservoir matrix, lateral conduction-limited thermal flux from the reservoir into the fracture, as well as thermal conduction and dispersion in the fracture. The model is applied to examine the mass of silica dissolved/precipitated along a fracture and to compute the change in fracture aperture. Results show that the maximum increase in the fracture aperture occurs near its inlet. A parametric study indicates that the reservoir thermal conductivity, reservoir porosity, reservoir effective diffusion coefficient, water velocity in the fracture, and the initial fracture aperture have dominant roles in quartz dissolution/precipitation mechanisms.