Mining is a high-risk, high-reward enterprise, the success of which is dependent on a range of factors. For companies involved in the exploration phase of mining, and for those in the capital markets who invest in mineral exploration, the risk-reward ratio and the problem of uncertainty is perhaps even more extreme.
And though uncertainty is pervasive, the JORC code means ASX-listed mining companies must abide by a strictly enforced uniform resource reporting standard and be as accurate and detailed as possible in their reports to investors.
Therefore, accurate information is the foundation for success, and whether it is an established mine looking to extend their reserves, or a company engaged in remote greenfields exploration, the enterprise with the sharpest picture and most comprehensive assessment of a zone of interest has the best chance of attracting and sustaining capital investment.
DDH1’s sophisticated deep hole directional drilling is pushing Australia’s technological capabilities in mine development and exploration further than anywhere else in the world by making assessments of potential resources more detailed, accurate and comprehensive than ever before. It achieves this heightened degree of intelligence through its innovations in directional drilling.
Working the Angles
The capacity to manoeuvre the drill bit and alter the direction of drilling deep underground rests on some remarkable technological innovation. AMR interviewed Murray Pollock, co-founder and Managing Director of DDH1, to gain some insights into the technology and techniques employed by the company in its directional drilling work.
“We use downhole motors to angle the drill holes as we descend. Internally, they are like a mono-pump,” Murray said.
“They have a very small, subtle bend right on the end, about half a metre behind the drill bit. Once the parent hole is drilled, we lower the directional bit to the bottom of the hole and then run a survey tool down and orientate that tool in the direction we want it to go. Sometimes we deal with live survey equipment down there but most of the time we pull that survey gear out. Once we start pumping, only the drill bit is turning and because it is on a slight angle to the rest of the tool it then drills off in the direction that we set it.”
Parents and Daughters
After drilling a single surface parent hole to a depth of around 1000m, DDH1 utilises its innovative directional drilling capabilities to branch out and drill a series of holes, termed ‘daughter holes’, to depths of 3000m and beyond. These holes intersect the target deposit from multiple points and angles.
In many cases, directional drilling allows the target deposit to be drilled at flatter angles than conventional drilling and increases the chances of not only intersecting areas of interest but also giving a truer indication of their width and orientation. This leads to more accurate modelling of the structure and quantity of any resource.
Hitting the Spot
Deep drill holes are the end result of time-consuming work required to define and ensure spatially accurate intersections of planned drill targets.
“At DDH1 we recognise that deep hole drilling is a costly business and those costs have been preceded by significant investment to identify drilling targets,” Murray said.
“Missing targets is not just about the cost of the hole but includes project opportunity costs when a critical decision is based on a drill hole result.
“Our emphasis is on personalised service to design and deliver accurate drilling programs that achieve our client’s targets. We are confident that with our best-in-class drilling equipment, on-rig spatial software and highly experienced personnel, that we can deliver optimal results.”
Service Holes Past 1km
DDH1’s directional drilling expertise is in high demand for drilling mine service holes to accurately intersect mine workings at very specific points.
“As a first step to most projects, we directionally drill pilot holes which are steered to the target using advanced gyro down hole surveying and the correct directional drilling equipment,” Murray said.
“These holes have been used for many purposes, such as to deliver paste backfill directly from a surface paste plant to the underground area, to lower large high voltage electrical cables directly from surface to deep underground, and to pump ground water from underground workings.
“Once the directionally drilled pilot core hole has broken through, the holes are then enlarged to accept a specific casing size. Enlarging the hole diameter is accomplished with down hole hammers and significant expertise is required to ensure that holes are not blocked up or lost.
“We generally find that if holes are into open mine workings, then spoil from the opening is allowed to drop into workings which minimises down hole compressed air requirements.
“Potential accuracy is typically within 1m over 1km and the directionally drilled core holes are then enlarged to accept pressure rated oilfield casing and grouted back to the surface.”
DDH1’s deepest single pass mine service hole is 1450m with multiple successful projects completed in excess of 1000m.
“Once a client gives us a target, our in-house team designs the holes using specialised software,” Murray said.
“Up at St Barbara (Gwalia) a few years ago, we drilled an electrical drop hole to drop a cable from the surface and it landed within 2m at a depth of 1375m.
“As another example, we helped on an electrical drop hole for a WA client, which involved a pilot hole to 1446m. This hole was opened to 12.25-inch, cased with a 9-inch diameter 100t oilfield casing string and grouted back to surface with 60m3 of grout. This hole is the deepest single pass cable drop hole in the Southern hemisphere and is now powering the deeper extensions of that mine.”
Oil and Gas to Mineral Drilling Crossover
The use of downhole motors is common practice in oilfield directional drilling, and DDH1 has taken this innovation from the oil and gas industry and transferred it to drilling for the mining sector.
“There is a sort of transfer of oilfield drilling technology and surveying techniques to mining,” Murray said. “We take things that are generally isolated to one drilling industry and move it across disciplines.”
DDH1’s versatility and competitive edge as a company comes from this ability to traverse both the oil and gas and mining industries, shifting and utilising technology from one field and applying it to the other, to offer clients greater efficiencies in their drilling programs.
“Something else that we’ve done over a period of many years is oil and gas exploration where we use mineral drilling techniques to drill first pass oil and gas exploration holes,” Murray said. “So, you get a transfer back the other way too. Most times an oil company goes out to drill a hole, they always assume it’s going to be a gusher and they’ll take a huge rig out with a convoy of semitrailers – the whole kit and kaboodle.
“However, for most of these holes we can take a mineral drilling rig and do the same hole for a fraction of the price and a fraction of the environmental impact. By doing it with a mineral rig you also get core all the way – right through the sequence – so the client ends up with enhanced geological knowledge, compared with a bucket full of muddy chips when they use a large oil and gas rig.”
Furthermore, DDH1’s capacity to operate under the stringent regulations governing the oil and gas sector means it can take on a range of jobs that might otherwise overwhelm standard drilling companies. Its recent work with Geoscience Australia is a case in point.
Deep and Complex
DDH1 provides highly specialised mine development and expansion expertise to extract mineral core samples at depths in excess of 3km. This type of work requires specialised knowledge, the right equipment, experienced personnel, meticulous planning and detailed safety systems.
“DDH1 is one of very few companies in the mineral drilling sector in Australia able to perform these services at such depths and its quality of equipment and productivity far exceeds that of its competitors in general,” Murray said. “In 2018, we drilled Australia’s deepest hole at Northern Star’s Jundee (in WA) of 3217m, a testament to the strength and technical expertise of the DDH1 team. Deploying Sandvik NHD heavy duty rods rated to 3000m, and using a 2500m-rated Sandvik DE880 rig, the drill hole extended 200m beyond the previous core drill record achieved at the Kalgoorlie Super Pit in 2015.”
Murray even said that if it wasn’t for Northern Star calling a halt, the company could have continued drilling past this record depth, which had a true vertical depth (TVD) of 2625.1m.
More recently, DDH1 won the contract to drill the deepest diamond drill hole in Australia. Artemis Resources is drilling a +3.3km “super-deep” diamond drill hole (ASD-1) to test rock sequences in the Pilbara Basin from surface to deep into the basement’s geology. The drill site has been prepared, pre-collared to a depth of 40m and cased ready for diamond drilling.
Other Directional Drilling Applications
“At the end of last year, we drilled a hole for Geoscience Australia for a new stratigraphic well in the Canning Basin,” Murray said. The Waukarlycarly drill site was identified off the back of data from Australia’s largest onshore seismic line which spans from central Australia to near Marble Bar in WA. This highlighted two areas of the Basin – the Waukarlycarly Embayment and the Kidson Sub-basin – which showed new mineral, energy and groundwater potential.
“We went down to 2680m to get the information. That sort of work was done under full oil and gas regulations. So, we were drilling with blow out preventors and they are high cost holes compared with the normal cord holes but a lot cheaper than taking an oil and gas rig in. And of course, with diamond drilling they had the evidence, they had the core,” Murray said.
Last year, DDH1 also partnered with KCGM to complete a highly technical drilling project at KCGM’s Super Pit in Kalgoorlie, WA, to allow for dewatering of the pit ahead of the planned mining schedule.
Two boreholes were successfully drilled for the placement of submersible pumps to remove excess water from beneath the pit. The project site was located at the Eastern end of the Boulder industrial area, adjacent to the Super Pit Lookout entrance – external to the pit to facilitate potential future expansions.
“The bore holes were drilled at an angle, targeting specific mine workings to access water while avoiding other old mine workings,” Murray explained. “The old workings are hydrologically connected to the pit, allowing them to act as a dewatering sump. Even though we drilled two holes, the diameter and placement of each hole means that either one is capable of dewatering the whole pit – we drilled two though, so one can be used for redundancy.”
Though ostensibly a drilling company, perhaps it’s better to think of DDH1 as an intelligence collection service, collecting the kind of core intelligence clients need to adequately assess a deposit. For companies listed on the ASX, this is vital. The consequences of not adequately adhering to the JORC code can be severe, including enforced retractions of statements.
DDH1’s sophisticated drilling of multiple intersections at flatter angles offers companies the most effective way to comprehensively map out and calculate the size, shape, orientation and grade of a JORC resource. In this way, companies and investors are not basing their decisions on limited information drawn from isolated drill holes.
More than that, directional drilling from the surface means drillers don’t need to re-mobilise rigs to drill multiple surface holes, reducing their impact on the environment, and drillers don’t need expend money on water, ventilation and electricity that drilling from an underground position demands.
DDH1’s skill and experience in the field is demonstrated by the remarkable accuracy of its drilling. Using sophisticated oilfield software and experienced planning, DDH1 can reliably hit targets at depths greater than 1,000m to one or two meters. Tasked with drilling an electrical drop hole for St. Barbara a few years ago, DDH1 drilled an intersection at 1,375m, landing within a couple of meters of the target. Deep hole drilling is an expensive enterprise. Missing targets costs money. With DDH1, this is something a client doesn’t have to worry about.
DDH1’s diamond core drilling can extract intact mineral core samples at depths of up to 3km. Mineral core is the chief source of geological information for exploration companies and other clients, and the ability to extract accurate and high-quality samples and properly orientated cores means DDH1 can offer a range of actors in the minerals sector expert guidance as they plan for the future.
Another innovation from DDH1 is their onsite photographic analysis of diamond core. Developed in-house through its work in the oil and gas sector, DDH1 offers clients high-resolution photography of mineral core in both white light and UV light.
“A lot of minerals fluoresce at different wavelengths, it’s just a matter of understanding which wavelength you are dealing with and making sure you’ve got the UV wavelength for that particular mineral,” Murray said.
“As we drill the core, we photograph it straight away in both white light and UV light – and with UV, hydrocarbons fluoresce. With a very low levels of hydrocarbons, you might not see them with the naked eye, but we can detect them with our photographic techniques. So, we are drilling and then photographing the core as soon as it comes out of the hole and we can transmit that data straight to the client’s head offices.”
Everything is set up on-site to photograph the extracted core and transmit the information to the client.
“We’ve got that all set up in what we term ‘Geoshacks’, these are shipping containers that we’ve lined and fitted out to a high level of operator comfort. We run the core across the back of the container, and we’ve got a dark room inside, so the core rolls in one side and out the other side, the operator is sitting in there taking photographs. It’s sort of a little facility that you send out to a hostile environment.” Murray said.
Along with incredible innovations in technology, DDH1 has the fleet necessary to handle even the most challenging jobs. “Within the DDH1 fleet, we’ve got 50 surface rigs and 10 underground rigs. Strike Drilling and Ranger Drilling are part of our group as well,” Murray said.
“Quality, safety and continuous improvement are our top priorities and we go to great lengths to ensure all of our equipment and staff are performing at optimal capacity. We operate Australia’s newest and most standardised high-capacity Diamond Core surface drilling fleet. We also have specialist rigs for complex engineering work and a fleet of underground rigs capable of drilling under flexible conditions.”
Most of them are Sandvik rigs, including the Sandvik UDR5000, UDR3000, UDR650, DE710, DE840 and DE880. Indeed, Murray is a big fan of Sandvik equipment, with a Sandvik DE880 the first rig used when the company started. “We have 20 DE880s, the particular rig used in the Jundee record-breaking drilling operations,” he said.
Whether drilling on a mine site or conducting exploration in remote regions, DDH1 will configure its operations, rig setup, safety management and personnel to optimise the drilling outcome.
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