Permeability of fractured tuff as functions of temperature and confining pressure

摘要

Understanding the transport properties of water through fractured rock is critical to predicting and modeling the hydrothermal performance of a geologic nuclear waste repository. Previous studies indicate that intact Topopah Spring tuff from Yucca Mountain, Nevada has a low permeability, (approximately) 1 (times) 10 (sup (minus)18) m(sup 2) ((approximately)1 microDarcy). A single fracture in the tuff increases the permeability to (approximately)100 (times)10(sup (minus)15) m(sup 2) (hundreds of milliDarcies). However, fracture healing may occur when high temperature water flows through the fracture lowering the permeability by one or more orders of magnitude. We report progress on laboratory experiments on permeability of fractured Topopah Spring tuff as functions of confining pressure, temperature, and water/rock ratio.