oa Mapping Fracture Connectivity Between Boreholes Using High Resolution Temperature Logs

The use of temperature logs in detecting fracture zones within a borehole is<br>sufficiently documented in the literature. This is an indirect technique and has been<br>used primarily for single-hole fracture characterization. Drilling fluid circulation and/or<br>groundwater movements induce temperature anomalies that are interpreted to indicate<br>permeable fractured zones. The use of temperature logs to map fracture<br>interconnectivity between boreholes is not well documented. This paper presents an<br>application of high resolution temperature logs in detecting fractured zones, mapping<br>fracture connectivity between holes and in monitoring groundwater movements. A<br>well system consisting of five vertical boreholes was drilled through sandstone to a<br>depth of approximately 55 m, one hole at each corner of a 7.62 m (25 ft) square and<br>one in the centre. These boreholes were drilled for experiments in connection with<br>mine technology development conducted by Centaur Mining Exploration Limited. High<br>resolution temperature logs and several other geophysical logs were acquired in these<br>boreholes with the Geological Survey of Canada R&D logging system. Borehole fluid<br>temperature logs recorded immediately after drilling and well development located<br>several water-producing fracture zones by their characteristic temperature signatures.