Non-sorbing tracer migration experiments on fractured rock at the Kamaishi Mine, Northeast Japan

摘要

This paper describes the design, implementation,and analysis of in situ tracer migration experiments in fracturedgranite. The research highlights the importance of geo-hydraulicinvestigations prior to performing tracer migration experiments.The authors conducted a detailed but simple investigation in orderto understand the spatial distribution of conductive fractures andthe pressure field. Seven boreholes were drilled in the test area,revealing hydraulic compartmentalization and a heterogeneousdistribution of conductive features. After identifying severalsuitable conductive fractures, three sets of dipole tracer migrationexperiments were conducted with various combinations ofinjection and withdrawal hole and dipole ratios. The tracerbreakthrough curves were analyzed using a streamline, analyticalsolution and numerical analysis of mass transport. Best-fitcalculations of the experimental breakthrough curves wereobtained by assigning apertures within the range of one to tentimes the square root of transmissivity and a dispersion coefficientequal to one-tenth of the migration length.