UTEM 4 Borehole
The UTEM 4 Borehole system - BHUTEM 4 - is a borehole EM system from Lamontagne Geophysics Ltd. with the ability to do simultaneous three-axis oriented down-hole UTEM measurements. Currently BHUTEM 4 uses a UTEM5 Receiver and the combination allows for data collection from up to three transmitter loops simultaneously. Three components from up to three different coupling angles - up to 9 different oriented components - in a single pass.
Orientation of the EM sensor is achieved by the combined use of three-axis magnetometer and temperature compensated three-axis accelerometer. The digital data are preprocessed down the hole, encoded, and transmitted to the surface by means of a single fibre optical link at a rate of 100k samples simultaneously for all components. Magnetometer data, accelerometer based tilt sensor data, temperature, and system monitoring data are multiplexed with the three-component EM data.
The key performance numbers of the system are:
- 3400m depth capability
- Very low deep hole system noise levels
- Very high system gain fidelity for "on" time measurement use
- Less than 0.05% late channel probe/receiver gain variation
The UTEM 4 BH system is composed of the UTEM 4 BH down-hole probe, the UTEM5 Receiver and up to three UTEM 4 or UTEM5 Transmitters. A field ready system would also include a BH UTEM winch, a winch motor controller, one or more fibre optic cable spools, inter-connecting cables, and wire laying accessories which are unchanged from those used in the BH UTEM 3 system.
The UTEM 4 BH down-hole probe has a maximum diameter of 38 mm for use in holes of BQ and greater diameter. The UTEM 4 BH data reduction and display software includes 3-axis data reduction oriented relative to a user specified drill section. Magnetometer, inclinometer and temperature data profiles can be plotted in addition to the EM data. Software is available for interactive 3D viewing of the vector fields.