It costs a sixth the amount of diamond drilling, a third the cost of reverse circulation drilling, and is quicker, safer and more environmentally friendly than most alternative drilling methods. Meet the RoXplorer® Coiled Tubing Drill Rig.
An oil and gas concept
Developed by the Deep Exploration Technologies Cooperative Research Centre (DET CRC) in collaboration with a team including Curtin University engineers, the rig has a malleable steel coil drill string that can be wound down on a reel, allowing for continuous drilling for up to 500m.
This is different to most other drilling methods, where the drill string is comprised of individual steel rods that must be manually connected and disconnected.
“The coil follows a guiding mechanism, which is fed down into the hole. At the end of it you have a water turbine, which rotates a custom-manufactured, diamond drill bit,” explains DET CRC and Curtin WA School of Mines: Minerals, Energy and Chemical Engineering Professor Brian Evans.
“The concept for the device comes from the oil and gas industry. Oil companies often insert coil tubing into oil wells with a device attached at the end called a ‘reamer’, which enlarges and cleans the oil well.”
The adaptation to mineral exploration poses a number of significant advantages for the Australian mining sector.
The RoXplorer is more cost effective than alternative drilling techniques because the lack of rod changes streamlines the process. Its use of coiled tubing makes it more versatile, as it can be used to deviate drilling horizontal holes without being moved from its location. It achieves better hole stability, because rod changes typically result in pressure variations, and it also removes a major source of injury, because drillers have been known to get their fingers trapped, or even severed, during manual rod changes.
Another advantage is the RoXplorer’s small size when compared with truck-mounted drilling rigs. The fact it weighs only 15 tonnes and the width of its tracks means that it has the environmental footprint of a ute’s tyres while it can also be transported on the road without a special permit. Evans estimates that the rig’s size and the fact it drills using fluids recycled through a solids removal unit means it has 10 per cent of the environmental footprint of a conventional truck-mounted drilling rig.
“Imagine this: we’re drilling around three times faster than we would be using alternative drilling techniques, and we’re doing it using technology that is totally conscious of health and safety issues and is environmentally far superior to anything ever been done before,” says Evans, excitedly.
The RoXplorer has already been recognised nationally, taking out an award at the 2018 CRC Association Awards for Excellence in Innovation, where it was described as “the most significant development in mineral exploration for 50 years”.
Successful field trials
Last year, the team conducted field trials on consolidated thick cover near Port Augusta, South Australia, and unconsolidated cover near Horsham, Victoria.
The trials demonstrated that the RoXplorer can drill both consolidated and unconsolidated cover at rates approaching 100m per 12-hour shift across multiple shifts with excellent sample return.
In further positives, the results of assays from the Port Augusta trial showed a strong match to those from diamond drill core from an adjacent hole, and it was determined that the Horsham trial presented challenging conditions that made the RoXplorer the only cost-effective option to drill the site.
“This new technology has opened the Gawler Craton, Murray Basin and similar areas of extensive cover to ‘prospecting drilling’ which will enable progressive vectoring towards concealed mineral deposits using multiple, cheap holes in a single drilling campaign, thereby opening the covered mineral exploration search space,” said DET CRC CEO Professor Richard Hillis.
The way forward
The RoXplorer represents a seismic shift for employees. As Evans explains, drillers aren’t hands-on with the RoXplorer: they operate it from a safe distance using a smart device.
This is also just the beginning. The DET CRC, Curtin and CSIRO are working together to develop an automated sampler that will accompany the RoXplorer and conduct assays in the field in real time, removing the need to analyse samples in a laboratory. Meanwhile, Curtin drilling engineer Dr Masood Mostofi is developing a new small-size cleaning cyclone device for the RoXplorer and a new drilling fluid system to control water loss downhole.
“We’re beginning to create a different kind of job for people with technology-based degrees. It’s very likely that we’ll be employing similar numbers of people but drilling three to five times as many holes,” Evans says.
Currently, only two prototypes of the RoXplorer have been developed, but it does have the potential to be commercialised. The first prototype is being tested by US company Barrick Gold, to trial the RoXplorer in drilling operations in Nevada. The second has been bought by Curtin.
“The Curtin prototype will be available as a research rig, which can be used by the WA government or various state governments to look for minerals in their states, while we develop it further to refine its automated drilling systems,” Evans says.
“This makes Curtin the only university in the southern hemisphere, if not the world, to have its own drilling rig.”
The additional time will also allow more postgraduate doctoral students from Curtin University and DET CRC’s partners – the University of Adelaide and the University of South Australia – the exciting opportunity to work with the RoXplorer.
“I think in total we’ve had 38 PhD graduates between the three universities, with their scholarships partially funded by the CRC,” Evans says.
Want to learn more? Visit the DET CRC website.