The EPICA borehole logger

The EPICA borehole logger has been developed in order to measure the characteristics of the borehole. The accuracy of the measurement allows the exploitation of data for scientific purposes. Developed on the mechanical basis of the Danish logging tool, completely new electronic equipment has been designed in order to measure diameter, pressure, temperature, inclination and azimuth. To check the good functioning of the embedded electronic equipment, additional parameters are transmitted: input voltage, input current, ADC temperature, pressure and power supply. A microcontroller supervises all data acquisition and transmission to the surface through the modem at every second. The logger uses a single conductor coaxial cable to supply DC power and transmit data. The surface computer displays and stores data and depth measurements. Two pantographs are used both to center the logger in the borehole and to measure hole diameter. For EPICA application, the drill is removed from the cable and the logger is connected to the anti-torque section and operated with the cable and EPICA winch. Complete records of the hole geometry and characteristics have been obtained successfully, at Dome C in the 1998/1999 and 2000/2001 seasons.