Borehole temperature logging for the detection of water flow

In a fractured rock body that is penetrated by a borehole, water flow along fracture planes and water flow between fractures, the borehole providing the pathway, produce different, characteristic thermal anomalies. Consequently, closely-spaced temperature measurements in a borehole allow quantitative estimates to be made of flow rates or velocities. Temperature measurements at depth intervals of as coarse as 3 m provide very useful information. Such logs can be obtained manually with lightweight field equipment that is capable of resolving temperature differences of approximately 2 mK. Some examples of the detection of water flow in boreholes of the Canadian Shield are given.