Abstracts

286 - Advances in the Application of Thermal Logging Techniques
for Hydro-physical Characterization of Flow through Fractured
Rock
Peter Pehme, Beth Parker, John Cherry & Jessica Meyer
G360 Centre for Applied Groundwater Research, University of Guelph, Ontario, Canada
Detlef Blohm
Instruments for Geophysics, Brampton, Ontario, Canada
The nuances of changes in the thermal field within the subsurface (i.e. magnitude and orientation
of thermal gradients, irregularities in temperature patterns etc.) are primarily controlled
by groundwater flow. The use of thermal hydro-physical techniques for identifying
groundwater flow in fractured rock is experiencing revitalization as a consequence of both
advances in sensors and synergistic developments of other technologies. Flexible impermeable
liners can be used to restore the ambient groundwater flow conditions that would
have existed without the borehole being present eliminating the distortion of temperature
logs caused by cross-connected flow between fractures and hydrologic units in open boreholes.
The active line source (ALS) technique, wherein the entire length of the static water
column in the lined-hole is heated and high resolution, temperature profiles are repeatedly
measured to observe the dissipation of thermal energy, overcomes the depth limitations
created by homothermic conditions while standardizing the basis for comparison of flow
zones thereby improving characterization of both major and subtle flow zones critical to
understanding contaminant migration and attenuation. More recently four sensors with
resolution approaching 0.001C have been incorporated in the magnetically orientated
thermal vector probe (TVP) to measure the vector components (magnitude and direction)
of the temperature field.
Examples of combining these techniques in sandstone and dolostone environments are
presented. The interpretations identify numerous hydraulically active fractures under both
ambient flow conditions and in response to pumping without a depth related bias. The
broad scale changes in the thermal regime are shown to provide an improved basis for
assessing the relative magnitude and direction of groundwater flow and variations akin
to subdivision into hydrogeologic units (HGUs) based on other data sets such as detailed
head profiles from multi-level systems.
210 - Palaeo-hydrogeological evolution of a fractured-rock aquifer
following the Champlain Sea Transgression in the St. Lawrence
Valley (Québec)
Marc Laurencelle 1 , René Lefebvre 1 , Michel Parent 2 , John Molson 3 & Christine
Rivard 2
1
Institut national de la recherche scientifique, Centre Eau Terre Environnement, Québec City,
Québec, Canada
2
Natural Resources Canada, Geological Survey of Canada (GSC), Québec City, Québec, Canada
3
Université Laval, Department of Geology and Geological Engineering, Québec City,
Québec, Canada
IAH-CNC 2015 WATERLOO CONFERENCE
79