The Distributed Thermal Perturbation Sensor: A New Tool for In Situ Estimation of Formation Thermal Properties and Geothermal Heat Flux
Abstract
Variations in geothermal heat flux provide a window into a diverse array of geological processes including plate tectonics and crustal fluid circulation. The Distributed Thermal Perturbation Sensor (DTPS) is a novel device that can simultaneously determine formation thermal properties and heat flux in situ. The device consists of a fiber- optic distributed temperature sensor (DTS) and a heat trace cable installed along the axis of a borehole. To operate the DTPS, the sensor is backfilled into a borehole and the disturbed thermal field is allowed to dissipate. A baseline temperature profile is subsequently recorded. Next, the heat trace cable is used to provide constant heating along the borehole and the thermal transient is recorded. DTS monitoring continues after heating concludes during the ensuing cool-down phase. To obtain in situ estimates for thermal properties and heat flux, simple conductive or conductive-convective models can be used to interpret the data. Given the 1 meter spatial resolution of the DTS - the DTPS provides thermal property and heat flux estimates at similar spatial resolution. To date, the DTPS has been deployed at three continental sites: (1) in the Amargosa Valley, Amargosa, NV, USA, to characterize groundwater flow through fractured volcanic tuffs, (2) in a deep permafrost boring within an Archean mafic volcanic belt at the High Lake Project Site (67°22"N, 110°50"W), Nunavut, Canada, and (3) as part of the monitoring program at CO2SINK, a carbon geosequestration experiment being conducted in Ketzin, Germany. The authors present results from these three sites and discuss potential modalities for future deployment in suboceanic environments.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFMOS34A..06F
- Keywords:
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- 1895 Instruments and techniques: monitoring;
- 3015 Heat flow (benthic);
- 3094 Instruments and techniques