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Accessible 3D modelling technology advances exploration geophysics for improved drill targeting
by CARMELA BURNS on March 9, 2012 technology
Geosoft introduced VOXI Earth Modelling, a geophysical inversion software service that generates 3D voxel models from airborne or ground gravity and magnetic data, at the PDAC 2012. Ian MacLeod, Geosoft Chief Technologist, also presented a talk entitled VOXI - A Cloud Approach to Earth Modelling for Exploration during the Geophysical Technical Session at the PDAC.
“One of the important benefits of converting gravity or magnetic data into a 3D earth model is that the visual end product allows explorers to see and understand the subsurface using now common 3D viewing platforms,“ said MacLeod. “VOXI produces a model of rock properties, which can be directly integrated with other surface and subsurface geologic observations."
Integration is important, says MacLeod, because no one technique provides all the answers. “Geophysical models often need to be constrained by geological and geochemical observations in three dimensions. Our aim as explorers is to develop the most complete subsurface picture of geology and mineral systems that we can."
The technique of modelling the earth through inversion has been used successfully within mineral exploration industry for well over a decade, and the benefits have been well documented. The ability to convert geophysical measurements directly into 3D images of the subsurface that can be integrated with other exploration information in three dimensions has enabled resource explorers to extract significantly more insight from their geophysical data. Insights generated from these 3D earth models have helped mineral explorers to sharpen their prospecting and improve their drill targeting, particularly in challenging subsurface environments.
The University of British Columbia (UBC) led the way when they established the UBC-Geophysical Inversion Facility in 1989 with funds from the B.C. Science and Technology Fund. UBC went on to develop modelling and inversion programs and utility codes that form the basis for most of the geophysical inversion solutions being deployed today in research institutes and large mineral exploration companies.
Over the past decade, inversion has proved its worth in exploring for major ore deposits around the world. Within mineral exploration, inversion modelling has aided in developing exploration potential within the iron ore and nickel belts of Western Australia; the Stuart Shelf and Olympic Dam in South Australia; iron oxide-copper-gold in Africa, South America and Australia; copper in Mongolia; and nickel laterite in Colombia.
The results have been impressive, however at present inversion remains largely in the hands of expert modellers, and the ability to generate an earth model that you can have confidence in is out of reach for most geophysicists. It’s estimated that less than 20% of mineral exploration projects use inversions despite the availability of advanced, high end inversion services and systems. With its VOXI Earth Modelling solution Geosoft is targeting speed, usability and accessibility to remedy this.
“We have designed VOXI Earth Modeling to fit naturally within an explorer’s workflow” said Robert Ellis, Geosoft Senior Earth Modelling Scientist that led the development of VOXI, “and we’ve made it fast, recognizing that speed in generating 3D inversions is a critical requirement that will allow geoscientists to use this tool routinely. Speed also allows us to iteratively improve our models as we add constraints and learn more about our projects.”
Behind VOXI Earth Modelling’s speed and agility is cloud technology engineered by Geosoft to conduct the complex geo-computing via the internet, with minimal drain on the explorer’s personal computer systems. The VOXI Earth Modelling cloud service is powered by Microsoft Windows Azure.
Included in the first release of VOXI Earth Modelling is Geosoft’s Magnetization Vector Inversion (MVI) modelling technique. MVI allows the magnetization direction to vary within the model and thus take into account the combined effects of remanence, demagnetization, anisotropy and induced magnetization. The result is a more realistic representation of rock magnetization, which is the fundamental rock property measured with the magnetic method.
Geosoft VOXI Earth Modelling is being offered as a software service extension accessible within Geosoft’s Oasis montaj 3D mapping and analysis platform. Once market availability is announced in April, Geosoft customers will be able to use the VOXI Earth Modelling service on a pay as you go or subscription plan.
Related Earth Explorer Articles:
Modelling the Earth through Inversion