Computer studies of heat tracer experiments in fractured rock

Abstract

The computer model PT is used to analyze a three-corehole recirculation heat tracer test conducted in a fractured granitic rock mass near Oracle, Arizona. Results of hydraulic tests and geophysical logs are cross-correlated =o determine the location, orientation and thickness of a high permeability fault zone, in which flow between the potencies during the heat tracer test is believed to occur. A quasi-three-dimensional model of fluid flow and heat transport in the fault zone is used to qualitatively reproduce a steep rise in measured temperature within a monitoring borehole. Computed thermal breakthroughs are found to be sensitive to two numerical grid parameters-- Thickness and width. A grid thickness of 1.0 cm and a grid width of 0.7 m are sufficient to qualitatively reproduce the steep temperature increase. Further research into the importance of heat convection under static conditions during the test is recommended.