FIRST LIBS PROTOTYPE BEGINS SIMULATED DOWNHOLE TESTING

The first real-time downhole assay prototype based on LIBS technology has reached the first stage of “real world” testing – analysis of a simulated drillhole in the lab based on real lithologies from the field.

The very ambitious aim of developing a novel, real-time downhole elemental analyser has reached an important milestone – actual testing in a simulated laboratory drillhole. The four main parts of the project that have been progressing in parallel – LIBS hardware, LIBS calibrations from real lithologies, dual-spectrometer software, and data analysis and modelling – are now sufficiently advanced that they will be incorporated for the first time into a real-time downhole analysis platform.

The LIBS hardware (laser, optics and spectrometers) has been incorporated into a very narrow probe that has undergone a variety of tests and is now ready to be lowered into an accurately-characterised set of drilled ore blocks and will allow elemental analysis of a vertically-oriented drillhole. The experimental setup allows for a range of contaminants to be introduced, as would be expected in a real drillhole.

The 21 accurately-characterised ore blocks have been evaluated by various independent analytical techniques and can be assembled vertically into a synthetic drillhole and used to compare the results obtained by the downhole prototype. Part of this work also involved developing LIBS calibrations for major and minor elements in our second LIBS lab at UniSA, further strengthening our understanding of LIBS analysis of typical lithologies.

The data analysis and modelling aspect of this project has a range of novel components incorporating artificial intelligence and machine learning. LIBS spectra will be degraded to various degrees by typical drillhole contaminants, and modelling the changes will give an ability to more accurately reconstruct the underlying composition.

Finally, bespoke software that allows control, acquisition and analysis of the dual-spectrometer hardware is now at the beta-testing stage, allowing spectral data to be instantly stored and handled remotely.

The ability to obtain real-time elemental composition of a deep drillhole will dramatically reduce the time taken for this analysis to be incorporated into a commercial exploration campaign. For the first time, it will allow the results of one exploratory drillhole to directly influence the decision for the placement of subsequent drillholes.