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doi:10.2204/iodp.proc.301.105.2005

Thermal experiments

The Expedition 301 downhole measurements program included several thermal tools. These tools are used to determine heat flow within sediments and to assess the thermal state of the borehole. Measurements within sediments should provide an indication of predrilling thermal conditions because the temperature tools penetrate ahead of the bit into undisturbed material. In contrast, measurements in boreholes can be strongly influenced by drilling operations, particularly if made soon after drilling. Borehole thermal data in basement are potentially useful, nevertheless, because they can indicate formation intervals that are likely to be hydrogeologically active. Data collected postdrilling from CORK observatories will be more useful for determining predisturbance thermal conditions in basement.

Estimation of heat flow also requires determination of formation thermal conductivity. Methods used during Expedition 301 for measuring thermal conductivity are described in "Thermal conductivity" in "Physical Properties."

Thermal tools

The APC temperature (APCT) coring shoe allows collection of temperature data without a separate tool run because the sensor and data logger are incorporated into the APC coring system. Details regarding operation and interpretation of this instrument are given in Shipboard Scientific Party (1992b).

The Davis-Villinger Temperature Probe (DVTP) requires a dedicated tool run on the coring line but can be run in sediments that are too lithified to provide good APCT tool data. A description of DVTP operation and data interpretation is provided in Davis et al. (1997).

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