b'AEGC 2023Short abstractsrefractive index, total and differential haemocyte cell counts,Ni through geochemical follow up on coincident magnetic and DNA damage and biochemistry. Tissue samples will also beGeoTEM anomalies.taken for DNA damage analysis. Lobsters will also be assessed for righting ability. The Jaguar Deposit is rare amongst Hydrothermal sulphide deposits, where nickel is not normally the abundant mineral in This presentation will discuss the results of the field trial and thethese deposit types. This benefits the use of electromagnetics, impact it has on future survey design. with mineralisation located within brittle-ductile structures hosted by felsic subvolcanic and granitic rocks, and not typical The practical application of wave equation based AVOmagmatic type or associated with black shales. Electromagnetic conductors nearly always directly relate to nickel mineralisation.Inversion.Centaurus Metals Ltd, taking over the project in 2019, initiated John Coffin and Panos Doulgeris a review of historic geophysical data including surface and Delft Inversion downhole electromagnetic data previously acquired by Vale between 2006 and 2010. This remodelling and interpretation of This talk demonstrates a wave-equation based method tothe EM data identified strong correlation between known nickel extract unique reservoir properties from seismic data. Genuineintercepts from drilling and aligning with interpreted structural seismic data will always have some degree of non-primarycontrols. The improvement in the interpretation gave Centaurus energy such as interbed multiples. Using Wave Equation Basedconfidence in the technique as a direct sulphide detection AVO Inversion (WEB-AVO) we consider primary reflections,method and was hence used as a primary tool in the companys together with interbed multiples, mode conversions andinitial exploration strategy.transmission effects. Notably different to conventional AVOThe use of surface and borehole EM has been a game changer inversion methods that assume primary reflections, an elusivefor Centaurus, assisting in doubling the resource in a relatively seismic reality. A significant differentiator for WEB-AVO is itsshort time, highlighting the potential for large depth extensions ability to work with a wider range of seismic gathers. possiblyto known resources and identifying several brownfields coming out of processing immediately after migration,opportunities. Deposit history and geophysical input to date is without special conditioning. The WEB-AVO results differ fromdiscussed with emphasis on the role that electromagnetics has conventional methods being layer properties of compressibilityplayed in the exploration and growth of the deposit.and shear compliance, rather than interface properties such as p and S impedance. Compressibility; the inverse of bulk modulus and shear compliance; the inverse of shear modulus, provide3D EM inversion of UTEM data to recover highly-a natural separation required for robust reservoir propertiesconductive targets.prediction. This separation is key when deriving porosity, saturation and lithology products. Devin Cowan Lindsey Heagy and Douglas OldenburgThe scope will include the fundamentals of WEB-AVO theory,University of British Columbiaimportant steps in a WEB-AVO project and a number of examples. The examples are drawn from onshore and offshoreThe use of UTEM systems to characterise highly-conductive Australia considering common challenges such as coal, marl andtargets for mineral exploration has become increasingly carbonate in a classic sand-shale sequence. In each situation thepopular over the past decade; both surface and borehole. UTEM primary wavefield at the target reservoir is being contaminatedsystems use a much longer period waveform than airborne by scattered energy arriving from the overburden. This normallyTEM systems, and are therefore more adept at capturing first presents as an unsatisfactory well-to-seismic tie and islate-time responses from conductive targets. Raw UTEM traditionally tackled through seismic data conditioning or welldata are generally transformed into representations that can log editing. However, in our examples we build alternativebe interpreted more effectively. And to characterise targets, elastic synthetics that consider the overburden and unravel howprogrammes like Maxwell are frequently used to fit subsets of the wavefield at the reservoir is actually formed. This techniquethe UTEM data with conductive plates. Due to the simplicity often improves the well-ties without further work and thenof the plate-model however, it can be very difficult to infer the applied as a part of the starting model for the WEB-AVOlocation, orientation and margins of complex targets. Here, inversion. Finally, we show a selection of the compressibility andwe are interested in recovering the distribution of electrical shear compliance inversion products derived. conductivities from surface and/or borehole UTEM data using 3D EM inversion. This approach allows us to recover conductive targets with more complex geometries and works to recover EM success in the Carajs: Geophysical results of theconductivity models that fit the entire UTEM dataset. However Jaguar Nickel deposit, Brazil. when attempting to recover highly-conductive targets, 3D EM inversion has several challenges. First, the numerical forward Grant Couston 1, Michael Adamson1, Roger Fitzhardinge2 andmodeling must be sufficiently accurate. As the conductivity of Grant Rocky Osborne3 the target increases, finer cells are required in the region of the 1 Southern Geoscience Consultantstarget. We must therefore consider mesh design when modeling 2 Centaurus Metals Ltd 3 Geosborne Pty Ltd highly-conductive targets. Second, UTEM data are only sensitive to regions experiencing sufficiently large induced currents. For The Jaguar Nickel Project, located in the Carajas Mineralhighly-conductive targets, the induced currents are confined Province of Brazil, is current classed as a hydrothermal Iron- to the outside of the target. And as a result, EM inversion has a Oxide Nickel Copper (IONC) deposit with a current resourcetendency to recover ring-like structures. In this presentation, we estimate of 80.6MT @ 0.91% Ni (Dec 2021). The deposit wasdiscuss the challenges of inverting UTEM data in 3D to recover discovered in 2007 by Vale S.A. during regional exploration forhighly-conductive targets. The numerical simulation is performed 89 PREVIEW FEBRUARY 2023'