Determination of Aperture Characteristics and Hydraulic Conductivity of Fracture Set Using Core Laboratory Tests

Aperture characteristics of fracture sets highly affects hydraulic properties of fractured rocks. Determination of fracture aperture and hydraulic conductivity is one of major issues for hydrogeological investigation on fractured rock aquifers. Exampling of a well site in central Taiwan with transmissivity of fracture set stochastically determined through a series of in-situ hydrogeological tests, this study carries out laboratory joint tests using the in-situ drilled rock core to further determine the joint roughness coefficient (JRC) of fracture plane. The aperture of various fracture plane is determined by emirical formula, and thus adopted to evaluate the hydraulic conductivity of the plane. The results show that the aperture of fracture with high dip angle resembles that of fracture with moderate dip angle under the overburden stress in study area. The aperture of farcture plane is dominated by JRC, which is a measured-size dependent variable. Finally, this study integrates test results obtained from laboratory and in-situ tests with testing scales to determine the equivalent mechanical aperture and hydraulic conductivity of fracture sets. The hydrogeological characteristics of the studied area is also addressed.