A new short borehole logging tool
A new borehole surveying tool was used to log the deep borehole at Camp Century, Greenland in July 1992. This new 6.35cm diameter instrument has a length of only 1m, allowing it to pass through bends in the sometimes highly deformed boreholes. The fluid filled borehole was logged to within 35m of be...
Main Authors: | , |
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Format: | Report |
Language: | English |
Published: |
Snow and Ice Research Group (SIRG), University of Nebraska/Snow and Ice Research Group (SIRG), University of Nebraska
1994
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Subjects: | |
Online Access: | https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2226 http://id.nii.ac.jp/1291/00002226/ https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2226&item_no=1&attribute_id=18&file_no=1 |
Summary: | A new borehole surveying tool was used to log the deep borehole at Camp Century, Greenland in July 1992. This new 6.35cm diameter instrument has a length of only 1m, allowing it to pass through bends in the sometimes highly deformed boreholes. The fluid filled borehole was logged to within 35m of bedrock, at a slant hole depth of 1350m. The inclination approached or exceeded 30° several times in the lower portion of the borehole. A microprocessor controlled data acquisition package (DAP) measures an internal and external thermistor and two orthogonally mounted inclinometers. The pressure transducer, which also includes a temperature measurement, and the fluxgate compass have independent microprocessor systems which are multiplexed through the DAP. A coaxial cable supplies DC power from the surface to the logger and provides MODEM communications between the DAP and a personal computer on the surface where the data from the DAP and slant hole depth data from the winch are used to compute a directional survey of the borehole. The surface computer provides plots of temperature, fluid pressure, hole inclination and azimuth as a function of true vertical depth as the hole is being surveyed. A set of centering springs can be easily added at the ends of the logging tool for use in boreholes where the inclination is less than 1 degree. |
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