Analysis of Crystalline Rock Permeability Versus Depth in a Canadian Precambrian Rock Setting

摘要

Over the last 50 years, there has been an increased interest in characterizing Precambrian crystalline rock, such as the Canadian Shield, to investigate the feasibility of deep geologic repositories for isolating used nuclear fuel from the biosphere. Extensive work has been conducted in Canada with a large amount of that work undertaken by Atomic Energy of Canada Limited. Few peer-reviewed journal articles were published based on these data, so a large amount of the data, specifically on fracture zones, are unavailable for modelers and analysts. By collecting and analyzing over one-hundred technical reports, journal articles, and conference proceedings, written between 1975 and 1996, it was possible to characterize plutonic Precambrian crystalline rock and separate the data into (1) equivalent porous media (EPM) for rock mass and (2) fracture zones (FZs). A third category, aggregate media (AM), was used herein to represent the entire data set (EPM + FZs). Using the data from these studies, a novel logistic function was fit to represent the mean permeability, with respect to depth, of crystalline rock for EPMs and FZs in plutons. Understanding rock permeability is critical for the long-term isolation of used nuclear fuel so that accurate predictions of fluid flow and mass transport can be evaluated in the area of the proposed storage location.