The geophysical survey is that all-important first step in mining and exploration. Companies must know where to begin and how to proceed. They must choose their approaches carefully.
Science and technology are at the core of good surveying. No aspect of the mining business has evolved technologically as much as surveying has. Recent advancements in aerial LiDAR, induced polarization, lasers, magnetotellurics and more are helping exploration companies find potentially mineable deposits. Science, as always, is proving to be a boon to the industry.
"There's been an advancement in terms of depth of exploration," says Roman Wasylechko, Director of Strategic Business Development at Abitibi Geophysics. "We've introduced a 3D electrode array, so we're looking deeper, collecting more data, and trying to get through the areas that have deep overburden to see what's in the bedrock."
Wasylechko remarks that the technology is particularly popular with gold explorers, who can now probe areas that "were left alone because the overburden was too deep" for previous technologies. "Now they can go back to those areas and have a look," he says, adding that Abitibi is "doing a lot more hole-to-hole IP (induced polarization). Really, we were quite busy last year doing hole-to-hole IP."
"Geophysics will find your targets of opportunity," says Keith Hall, Chief Operating Officer of Pico Envirotec. By that he means it can point you to where there might be a rich ore deposit, but the key word is might.
“The only thing that we can really find absolutely would be uranium,” Hall adds. “Uranium is radioactive, and it’s radioactive in a specific way and we can detect that. All the other geophysical tools – magnetometer, spectrometer, gravity systems, EM systems – are tools of assistance for finding targets of opportunity.”
He says geophysical surveying has changed much largely by way of fine-tuning for better results. “Essentially, with the exception maybe of time-domain EM systems, all of the sensors, if you will, that are being used today are actually the same sensors that have been used since the early ’50s. The cesium magnetometer sensor, for instance, hasn’t really changed since it was invented.
“But what has happened over the last decade more than at any time previously is, our ability to measure the data that’s coming out of these sensors to greater degrees of accuracy and resolution has increased a great deal. The advent of miniaturized computers has enabled us to do things that a decade ago would have got you laughed at (if you had claimed those abilities). The basic sensors themselves haven’t changed, but our ability to use them with greater precision has increased dramatically.
“Instead of being able to measure to one part in a thousand,” he adds, “we can now measure to one part in a billion. There’s two schools of thought that say ‘How far do you really need to take this?’ … Just because we can doesn’t really mean that it gains us a whole heck of a lot.”
Furthermore, Hall notes how rapidly evolving technology has greatly improved what is done with the data that surveyors collect: “What’s happened in the last decade is the huge improvements that have been made in data processing software, and the ability to apply many different interpretation techniques to the data that’s been acquired from the sensors. … Advances in computing power allow us to handle literally gigabytes or even terrabytes of data that would have been virtually an impossibility 10 years ago.”
Colorado-based Condor Consulting has successfully exploited that boom in data-processing capacities to offer its clients sophisticated interpretations of the binary information that comes out of surveys.
Ken Witherly, Condor’s President, says one major advance has been in the ability of firms such as his to create useful, illustrative graphic representations of what the surveyors have found. “We can now do that cost-effectively for a whole range of data – all the major types of surveys. That allows more effective use of the results. It allows easier communication of those outcomes.
“A lot more exploration is focusing in on targets of greater depths than before, and so you often don’t have the same degree of geological information,” he continues. “You’re relying a lot more on subsurface imaging, so being able to communicate those results clearly to your clients, and then the clients to their investors and shareholders, is important.”
He says the considerable strides forward in geophysical surveying are attributable to a number of factors. “It’s like (Hall) said, the acquisition systems have increased in number and to some degree in complexity, but it’s probably more that there’s more of them and they’re more reliable. You can perform surveys around the world with a degree of quality that 20 years ago was very difficult to achieve.”
There’s a worldwide “level playing field” in surveying now, Witherly says, partly because “there are more systems and more service providers – it’s more of a commodity than a speciality.”
Witherly explains that processing is just a part of what Condor does for its clients. “It’s also the integration and the explanation of those outcomes in terms of what the client is looking for. It’s not simply the task of transforming the data. It’s moving it into a space where you’re actually trying to define what geologically is happening. So we put a lot of time and effort after the processing is done in actually trying to understand what the results of the processing mean in light of what the client is looking for.
“We work with our clients to get the maximum value out of the information so that they can advance their exploration program.”
Hall says especially great improvements have been made in EM and spectrometer surveying. “Time-domain EM has really come into its own over the last decade, maybe even the last five years, with the ability to measure to greater and greater depths. Some of the new time-domain systems are claiming depths of 1,200 or 1,300 metres in penetration. … Certainly, they can image geophysical information from far greater depths than they could five years ago.”
McPhar International, founded decades ago in Toronto but now a member of the India-based Neterwala Group, is one firm that has benefited from leading-edge technologies of Hall’s Pico Envirotec. The geosurveying firm used Pico’s self-contained, high-resolution AirMag magneometer system in an airborne survey of kimberlite territory in India, to cite just one example.
“We started using Pico systems in about 2003, and we’ve been steady users ever since,” McPhar President Tim Bodger says from Toronto, adding that the firm’s current owners are content with the systems in use.
In other words, they like the direction it’s taking them.
