Drilling set for radical change

DRILLING for minerals could change radically in the next few years thanks to technology now being developed in Australia. By David Upton
Drilling set for radical change Drilling set for radical change Drilling set for radical change Drilling set for radical change Drilling set for radical change

The chief executive of DET CRC, professor Richard Hillis. Courtesy of the University of Adelaide.

Staff Reporter

Adelaide’s Deep Exploration Technologies Cooperative Research Centre was set up less than 18 months ago and is yet to attract a high profile, but it’s no lightweight.

With $120 million of cash and in-kind funding from the federal and state governments and a who’s who of industry partners, DET CRC is mounting the world’s biggest independent R&D effort into drilling technology.

The centre has a radical vision for the future. Drill core will be almost redundant, with downhole sensors providing all the information ever yielded by core.

This data will be available in real-time and transmitted to geologists anywhere in the world, where they will refine their geological models while drilling is in progress.

And it doesn’t end there.

The more than 100 year-old steel drill rod would be replaced by continuous coiled steel tubing, or perhaps even continuous coiled carbon fibre tubing, that could be steered underground as information about the location of mineralisation is developed real-time in parallel to drilling progress.

How far away is this scenario?

The chief executive of DET CRC, professor Richard Hillis, told MiningNews.net that parts of this scenario were already possible.

“However, in terms of fully transformational coiled tubing drilling technology and real time sensing and modelling, we hope to see that implemented by the end of the CRC in 2018,” he said.

The centre is already hitting some milestones along the way, with the announcement last week that the world’s first carbon fibre drill rod used in mineral exploration has successfully drilled through 100m of hard rock at DET CRC’s drilling research and training facility at Brukunga in the Adelaide Hills.

The carbon fibre drill rod, produced by Queensland-based Teakle Composites, weighs only 7kg compared to 17kg for a steel rod of the same length.

The DET CRC team has already embedded an orientation sensor in a carbon fibre rod and the next stage will be to lab and field-test the carbon fibre rod with an embedded sensor to obtain hole orientation data in real-time, without a separate deviation survey.

Other sensors will follow.

Hillis said the full suite of sensors would enable explorers to collect all the information yielded by core regarding the rocks they are drilling through and also about potential drilling hazards.

“Until now this has not been possible as it is very difficult to embed sensors in steel rods. Also, steel would interfere with the operation of many of the sensors required to detect subsurface mineralisation”

Hillis said drilling was the biggest spend in minerals exploration and therefore the primary focus for DET CRC.

“We can’t transform drilling without transforming the analysis of the hole. So we began by asking whether mineral explorers would always want to cut core. It’s a key question because the analysis of core is very time-consuming.

“It takes weeks or even months to recover core, get it to the lab and get assay results. If there’s something interesting you then have an expensive rig remobilisation to the original drilling site for a follow up drilling program.”

Hillis said core could only be replaced if the sensors provided data that matched the information that core provided.

“So our programs are aimed at providing geochemical, mineralogical and petrophysical information through a variety of sensors either on a wireline tool or in the drill rod. We also want to provide an image of the borehole. Image logging is already being routinely undertaken in the petroleum industry.

“The research on downhole sensors is being complemented by a major ‘lab-on-the-rig’ project. We are also investigating what sensors can be put on the rig, at the top of the drillhole for near real-time information”

“There may always be a need some need for core for calibration/validation. But the amount of core required could be dramatically reduced, creating huge savings.”

Hillis added that cutting and analysing core not only reduced productivity, it limited the drilling techniques that could be applied and closes off valuable opportunities for revolutionary new drilling technologies.

“For over a hundred years we have screwed together pieces of steel pipe to make up a drill string and get to the bottom of the hole. If you’re 1000m down you need 300 pieces of steel pipe to be screwed and unscrewed if you want to change the bit.

“It’s slow, there are safety risks from manual handling of so much pipe and the drill pad has be set up to accommodate laying down and picking up of pipe. We also still rotate the entire drill string to rotate the bit. This is very energy-inefficient.

“We want to develop a coil tubing rig for mineral exploration, based on similar technology that is already used in the coal seam gas industry.

“Coiled tubing drilling has a much lesser environmental impact because the steel pipe is on a coil and unwinds from a large drum. Nobody is screwing pipe together, so you save time. You can change a bit at depth in minutes, not hours.”

Coiled tube drilling utilises downhole motors just behind the bit and the whole drill string is not required to be rotated in order to drill at the bottom of the hole.

This permits complex drilling trajectories and allows geologists to “chase” their targeted mineralisation. Again, this technology is already being used in the petroleum industry. DET CRC’s target is to deploy this kind of drilling, with downhole and/or lab-on-the-rig sensing in mineral exploration at a cost of $50/m – much cheaper than current diamond drilling costs.

The crossover of technology from the petroleum industry is no surprise, given Hillis’ previous role as head of the Australian School of Petroleum at the University of Adelaide.

The petroleum industry is a logical place to look for ways to improve productivity in mineral exploration drilling, given that petroleum explorers may spend 100 times more on an onshore well than the cost of a minerals industry diamond drill hole, and another 10 times more again when it comes to offshore wells. The drivers for productivity gains in petroleum drilling are even greater than those in minerals drilling.

Borrowing some of these technologies and heavy investment by DET CRC in innovations of its own could bring about a revolution in minerals drilling that many in the industry have yet to even see rushing towards them.

This article first appeared in ILN's sister publication MiningNews.net.