2024 Q2 technical highlights

This episode features the following technical highlights:

• Our Moonera National Drilling Initiative campaign in collaboration with the Geological Survey of WA;
• CT ‘dogleg’ experiments to assess sidewall coring and multiple deviations from the same drill hole;
• First downhole LIBS prototype field trial successfully completed  at the Australian Automation and Robotics Precinct, WA.

MOONERA NATIONAL DRILLING INITIATIVE IN COLLABORATION WITH THE GEOLOGICAL SURVEY OF WA & DIG CT

Contact our Project Leader: Richard Chopping (GSWA)

MinEx CRC has drilled 5 holes through the thick and challenging cover of the Eucla Basin on the Nullarbor. This retrieved new samples of the cover sequence, adding to previous stratigraphic drilling in the region, with one hole reaching 501m depth.

The National Drilling Initiative aims to provide precompetitive data to help exploration success in under-cover terranes, and retrieve new rock samples from never-studied areas. The Nullarbor is one of the most challenging drilling locations in Western Australia, and we have successfully demonstrated the use of the CT technology to provide both chip and core material down to beyond 500 m.

Over the past few months, the 500m RoXplorer CT rig has been operating near the Moonera pastoral station on the Nullarbor plain in south-eastern Western Australia. With the thick, limestone-dominated cover of the Eucla Basin obscuring the basement, drilling is critical to testing geophysical interpretations of basement geology.

This program under the NDI fills in a gap in the stratigraphic drilling program undertaken by GSWA in 2014–2015 which showed significant basement prospectivity for nickel and other critical minerals. GSWA tested the ability of the novel CT technology to drill through the ~500 m of cover in order to see if basement could be intersected.

The program has not been without its challenges. Unprecedented rainfall of nearly 300 mm in a week – what the area normally receives over a whole year! – flooded out the drilling. The cover sequence has also presented difficulties with a hard near-surface cap, numerous cavities, and a tendency to fracture behind the bit.

This program drilled two deep holes by the RoXplorer, plus 3 others to nearly 100 m each. The deepest hole reached 501 m, and from ~100 m depth core was selectively retrieved through the cover sequence to the bottom of the hole. These samples provide a unique perspective on the cover sequence and provide unprecedented insight to help explorers reach basement targets.

CT ‘DOGLEG’ EXPERIMENTS TO ASSESS SIDEWALL CORING AND MULTIPLE DEVIATIONS FROM THE SAME DRILL HOLE

Contact our Project Leader: Soren Soe (UniSA)

MinEx CRC is developing “dogleg” technologies to collect three metre sidewall core samples from selected depths within a coiled tubing drill hole.  The technology will also enable multiple deviations from the same drill hole.  The technology is being trialled at the historic Kapunda Cu mine site in collaboration with MinEx CRC Affiliate EnviroCopper.

MinEx CRC Participants have set our drilling engineers the ambitious task of delivering a coiled tubing (CT) drilling platform and with sample integrity comparable to diamond drilling.  The best way to close the discussion on core-quality sample integrity is to deliver an actual core sample.  We have already achieved bottom-of-hole core drilling, delivering 3 to 9m lengths of core from multiple drill holes in three drilling campaigns.  The “dogleg” experiments will go a step further by enabling explorers to take sidewall cores from any depth and create kick-off points for multiple deviations from the same drill hole.

The project team has reviewed available technologies for delivering a side wall core sample, including side wall systems (which utilise micro-coring perpendicular to the bore hole) and various side track systems (which utilise a wedge or calliper to kick out into the side wall).  This has allowed us to choose the most appropriate technology and modify it for drilling with the MinEx CRC RoXplorer drilling platform.  Initial experiments conducted in soft cover rocks at the UniSA Mawson Lakes campus were promising.  The Kapunda trial will test the technology in basement rocks more appropriate for sampling in hard rock mineral systems.

The ability to collect sidewall core samples will allow explorers to take high-quality samples (including textural and structural information) from selected intervals, informed by prior analysis of the drill cuttings from the same hole.  This approach retains the cost benefits of CT drilling whilst enabling flexible sampling options.   At the same time, creating the option for multiple deviations from one borehole will help explorers to chase and hit small, complex targets at depth – for example to intersect an off hole geophysical target.  In doing so we will minimise the number of drill pads required and the number of meters drilled through challenging cover rocks, thus reducing the cost and environmental impact of drilling.

FIRST DOWNHOLE LIBS PROTOTYPE FIELD TRIAL SUCCESSFULLY COMPLETED

Contact our Project Leader: Jess Stromberg (CSIRO)

MinEx CRC has conducted a successful first field trial with our downhole LIBS prototype system at the Australian Automation and Robotics Precinct, WA.

LIBS is an acronym for Laser Induced Breakdown Spectroscopy – a technique which uses a high powered laser pulse to generate a plasma on the sample surface which can be measured to determine quantitative chemistry at sub-millimeter scale.

Demonstrating the fidelity of the prototype LIBS downhole assay tool outside of a lab environment is a key step in moving the tool up the technology readiness levels and will inform further development of the system towards a commercial offering within the next three years.

MinEx CRC is focused on developing a new set of exploration tools that add value to drilling and inform decision making through new subsurface geological knowledge. This field trial is the first demonstration of the generation of rapid, spatially resolved downhole multi-element geochemical information using the downhole LIBS prototype below 10 meters.

After extensive laboratory testing, data analysis work, and hardware and software development, the downhole prototype LIBS system is field ready and has been deployed in a drill hole outside of the laboratory environment.

The prototype LIBS system comprises a novel downhole tool with a ruggedized chassis and in hole stabilizers, which with the winch system, is controlled by bespoke software that allows for spectral data to be handled remotely and visualized as downhole logs in near real time. The system also includes an in-field calibration module and additional sensors for monitoring instrument performance. In this first field trial, the system was deployed on a wireline and generated multi-element downhole logs in near-real time.

Download the pre-commercial product brochure for this technology below.