Research in Geophysics Instrumentation is currently ongoing in the following areas.
- Nuclear Geophysics
- Electric and Magnetic Downhole Sensors
- Communication Networks and Data Acquisition
The Geophysical Instrumentation Group develop innovative borehole logging, logging-while-drilling and seismic technologies for the mining industry. Our research is focused on developing robust and accurate sensors for measuring formation magnetic, electrical and sonic properties, bulk density measurements using nuclear techniques and rock mass characterisation.
The increasing costs associated with the discovery of new mineral deposits has forced industry to consider the role of advanced exploration technologies and techniques in improving efficiencies across exploration spectrum.
Recording and processing geophysical data while drilling boreholes can lead to significant cost savings for an exploration company. Information such as formation density and elemental composition can indicate whether an interesting mineral zone has been intersected. To this end, a new approach to in-situ elemental analysis is being developed using the technique of prompt gamma neutron activation. Neutron radiation can make a formation temporally radioactive with the resulting spectrum of gamma rays being indicative of its composition. We have recently purchased a pulsed Deuterium-Deuterium neutron generator to characterise this technique in the laboratory before moving on to the development of a field-deployable tool.
The group was also involved with the development of the TruProbe autonomous gamma probe, which measures total count gamma radiation in a borehole. The tool can be operated and deployed by the drillers, which helps to remove the need of employing costly external contractors to conduct geophysical surveys. In addition, we also developed the first logging-while-drilling spectral gamma ray sensor for minerals exploration, the Autoshuttle. Both the Autoshuttle and TruProbe are currently being commercialised by Boart Longyear, a global exploration company.
Electric and Magnetic Downhole Sensors
Nuclear methods are not the only way to get in-situ information about rock properties.
A rock’s electrical and magnetic signatures are important measures of mineralogy and overall geology. Another research strand within the Geophysical Instrumentation Group is to develop robust sensors, for slim-hole applications, to measure galvanic resistivity and magnetic susceptibility.
We have already developed downhole magnetic, and resistivity sensors, which can be deployed at the end of a diamond drill string and record the local magnetic field and resistivity of the rock as the string is removed at the end of drilling. Our current research efforts are focussed on making these sensors more robust and accurate.
Communication Networks and Data Acquisition
The need to record and integrate data from all aspects of the operation of a mine, from drilling, blasting and ore extraction to hazard management means that increasing volumes of real-time information need to be acquired, processed and transmitted to a central location in order to facilitate monitoring and efficient decision making. We are currently developing a novel low power high-speed data transfer wireless network, which will have applications not only to mining but also in any environment where distributed data is important. The network size can be dynamically changed when nodes are joining or leaving the network with each subnet can support up to 400 nodes with the communication speed approximate 125 kbps.
Power line communication is often required in many mining borehole logging applications. A power line communication module that capable of sending and retrieving data over 2.4 km wireline at 19,200 bps has been developed by our group