Fracture alteration by precipitation resulting from thermal gradients: Upscaled mean aperture-effective transmissivity relationship

Abstract

Precipitation and dissolution reactions in fractures alter apertures, which in turn affects their flow and transport properties. We consider aperture alteration by precipitation in a "gradient-reaction" regime where fluids are close to chemical equilibrium with a mineral everywhere, but precipitation is driven by solubility gradients. Monte Carlo simulations on computer-generated aperture fields suggest that the most important feature of fracture alteration by precipitation is the formation of elongated precipitate bodies perpendicular to the mean flow direction. The simulation results provide a basis for a proposed upscaling relationship between mean aperture and the effective transmissivity tensor, incorporating a critical aperture at which the transmissivity decreases steeply. © 2012 by the American Geophysical Union.