Not only does the initiative aim to increase the drilling speed for mineral exploration from 50 revolutions per minute (rpm) to 7000 rpm but it is expected to reduce the cost of drilling boreholes to $50 per metre and the number of staff involved as well.
Professor Brian Evans, who leads the project at Western Australia’s Curtin University through its Department of Petroleum Engineering, said the research team was adapting the coiled tube drilling rig technology currently used in the oil and gas industry, which allows for continuous drilling as there is no need for rod changes.
“We are adapting these coiled tube drilling rigs to be used for hard rock mineral drilling by replacing the steel drill pipe with flexible coiled tubing, and working on embedding sensors and electronic chips in the composite laminate tube, so logging can be done in real time,” he said.
“We’ve also decreased the borehole size because by drilling continuously with small, low-cost impregnated diamond bits and increasing the speed, we are hoping to increase the rate of penetration substantially.”
According to Evans, the project was initiated about four years ago by AMIRA International, an organisation of minerals companies and suppliers that develops, brokers and facilitates collaborative research projects.
“Their [AMIRA’s] initiative was awarded with funding from the Federal Government, companies and universities in the development of the Deep Exploration Technologies Co-operative Research Centre,” he explained.
The DET CRC-led project, which now has $5.9 million in cash funding and more than $9.7 million in in-kind funding, has expanded to become a partnership between the CSIRO, Curtin University and three drilling suppliers – Boart Longyear, Imdex and Teakle Composites.
Benefits for the quarrying industry
While the research so far has revolved around mineral exploration and mining, Evans confirmed to Quarry that the technology would have an immediate application in the quarrying industry.
“I imagine that the coiled tube rig would simply walk along the drill hole pattern and punch down the hole without any need for rod changes,” he surmised. “This may reduce any quarry to having a single rig rather than multiple rigs, and where the driller is also the shot firer, the shot may be loaded immediately after the hole is drilled, bringing new economies of scale to blasting.”
Expanding on how the researchers intended to increase the rig’s drilling speed by more than 100 times, Evans explained that the use of high speed water turbine operations would make it easier to drill hard rock faster with small diamond impregnated bits or hammers.
“While the hole diameter is reduced to 44mm, the water pump power has to be increased,” he said. “There are many more changes to be made to this new paradigm in drilling but we are working on these technologies.”
It was said that the elimination of drill rods – and, thus, rod handling – would facilitate a safer worksite, with Evans adding that only two people were required to operate a coiled tube drilling rig. This was in comparison to the four or more people needed for a conventional large minerals rig, and it is believed that the reduced number of operators could help reduce occupational heath and safety risks as well as operational costs.
Evans said there was potential for the drilling technology to become fully automated as well. “The drilling process could become remotely controlled, with no person manning the rig, which again would be useful in a quarry setting,” he said.
Additionally, the technology could offer environmental gains. “The footprint for this drilling rig is very small, and may be developed as equivalent to two large trailers compared with the large footprint of typical drilling rigs,” Evans commented. “The small footprint and rapid drilling means less impact on the surface environment.”
A prototype of the adapted drilling rig was trialled on Thursday, 20 November at the Brukunga pyrite mine site east of Adelaide. While Evans said the research team hoped that the drilling rig would become available commercially through Boart Longyear by 2018, he noted that there were still many issues yet to be resolved, such as the development of an appropriate high speed drilling fluid filtration system.