The Role of Pressure Solution in Fracture Healing: A Multi-Scale Reaction-Flow Modeling Approach

摘要

A multi-scale model is presented to investigate the healing of fractures in sandstones as a result of pressure solution (PS) mechanisms. The multiple scales include the grain-grain contact scale where the kinetic dissolution of minerals and the diffusion of dissolved species occur and the bedding scale in the vicinity of a fracture where mineral precipitation, transport, and the macroscopic stress field control the system. Using parameters from independent experiments on quartz dissolution/precipitation kinetics and diffusion in thin water films, the model is calibrated with experimental data from chemical compaction experiments and with observed porosity vs. depth trends in sedimentary basins. We present quantitative results highlighting the extent and time scales of fracture healing. We discuss the influence of the controlling mechanisms of PS (diffusion, precipitation or mixed-controlled), of fracture healing (diffusion or flow controlled), and the influence of the stress field close to the fracture (fracture stiffness).