AEGC : Brisbane 2023 Workshop
March 14th, 2023
January 31st, 2023
Des FitzGerald, Jeff Thurston, Mike Morse, Rainer Wackerle, Seda Celebier, Rod Paterson, Clive Foss, Ed Beigert
Back to The New Basics
A ONE-DAY WORKSHOP
Uplifting Survey Data – The good, bad and the ugly of data
Rainer Wackerle and Mike Morse
After 25 years, and 5 major compilation efforts, the Australian continental scale magnetic grid is being audited for the quality of the underlying key 250K survey line data. Initially the aim of the continental grids was to get coverage, accepting good, bad and indifferent surveys; which formed the first edition magnetic map of Australia, but this was quickly shown to have issues. The reality now is that uniform quality is now required and expected as inputs to, and as result from the the continental magnetic grids, given it’s pivotal role in exploration. A start has been made on checking all the surveys which have been archived and processed over the years. Our demonstration will cover the concerns for the range of errors in the magnetics and radiometric data, as well as the complexities and costs of auditing such work. To provide an example, almost all of the NT data acquisition projects have data structure and/or navigation problems, which are addressed to produce a preliminary NT dataset with the following properties:
Consists of individual surveys.
Lines and tie lines in the same database.
Plots in their correct position in the Northern Territory.
Each survey consisting of a set of unique line numbers.
Each line having a monotonically increasing fiducial number sequence.
A second phase of this work is on-going, and examples and reports of progress will be discussed for Victoria and NSW. And in the age of machine-learning, we will discuss how better quality metadata is derived.
Feature Extraction – Cauchy Derivatives and stable downwards continuation.
Des Fitzgerald and Jeff Thurston
We will outline how fundamentally improved algorithims and more complex workflows, that honor the underlying physics, continue to evolve.
Magnetic Transects – An application to basalt flood plains, to find depths and thicknesses of more than one flood event.
Euler Deconvolution Improvements – stabilizing the solutions for signal hot-spots by using Hilbert transforms.
Multi-Scale edge Detection (WormE) – improved extraction of contacts and dips for large scale features with an application to the Darling Fault
Dyke recognition – application in the Broken Hill district
Cauchy Derivatives by Integration – providing higher order derivatives of potential fields, using 100 year old theory. Application in both 1D/2D line and gridded data.
Automation -All techniques will be shown using a desktop interface, and all capabilities will be mirrored via the Protobuf messaging + Python scripting. A jump into 3D context will be discussed throughout.
Hard rock and soft rock, exploration strategies.
A discussion in the advancements, tip and tricks for deriving a candidate 3D Model from 2D geology maps. Case Studies for the Mansfield Syncline (with addition of Magnetic Data), Brockman Syncline and Platreef platinum style deposits are used for illustration.
Stochastic modelling and inversion using magnetics and geological constraints.
We will review the magnetic inversion specifically using the stochastic inversion method with or without geological constraints and how this can assist in drillhole targeting. We show how geological constraints can be derived using some of the magnetic methods being discussed in this workshop. This information is used to build a geological starting model. We demonstrate how this can help constrain the stochastic inversion and how the derived model uncertainty can be used to design and optimise future drilling campaigns. A case study with a focus on IOCG and Cu/Ni/PGEs.
Analysis and inversion of magnetic field data with expression of remanent magnetization .
This session with start with advice as to how recognize remanence contributions and make preliminary estimates of magnetization direction from visual inspection of magnetic fields both across Australia and globally. We will then review the application of magnetic field transforms to variously enhance or mitigate the expression of remanent magnetization in magnetic field data and systematically evaluate the capability and limitations of recovering magnetisation direction estimates from magnetic field inversion. Through the workshop we will investigate 12 different magnetic field anomalies due substantially to remanent magnetisation. Finally, we will look at the Australian remanent anomaly database – a freely available web based utility highlighting magnetic anomalies across Australia due to remanent magnetisation and providing a download of inversion models and results.
Kill or Drill – Magnetic Technologies and Attractive Decisions
In this workshop you have learned about advances in tools, techniques, inversion capabilities, and data resources enabling better integration of magnetic data with geology and other geophysical data to enhance your exploration and optimise drilling campaigns for improved economic performance.
After a brief review and summary, you will step into the role of Decision Executive and use your newly acquired skills to make early “kill or drill” decisions in a fast-paced game of skill and chance. You will discover how magnetic technologies and improved techniques can steer exploration and exploitation decisions in several examples and case histories.
What are the learning outcomes?
You will become updated on Magnetic methods for exploration, which have had many significant improvements. Learn how cutting the usual corners is no longer necessary due to improving computation capabilities. There will be a discussion about better uplifting and higher quality requirements for survey data and how signal processing is propelled towards embracing more appropriate physics for potential fields, away from previous simple approximations.
The practical workshop will show real case studies and forward models to demonstrate the extraction of geological sections from standard airborne magnetic datasets.
Who should attend the workshop
People who use magnetic survey data for green field exploration mapping and brownfield mapping around producing mines.
Des has over 30 years’ experience with Intrepid Geophysics as owner, pioneer and now, Chief Scientific Officer. His major projects have included:
The development of the Intrepid software, for geophysical processing, with Geoscience Australia (GA)
A complete compilation of the Australian regional geophysical maps (both on-shore and off) for magnetics, gravity and bathymetry in partnership with Geoscience Australia.
The liaising with the French Geological Survey to further develop and promote new technology for 3D Geological mapping, known as GeoModeller, with potential field geophysics.
Des holds a PhD in Mining Engineering from the University of Melbourne. And has been an influential members across a number of groups such as Spatial Vision, RMIT Innovation Ltd, and GeoJAG.
Creative Problem Solver | Thought Leader | Stratergist Enabling cost-effective oil and gas exploration. He sits on the Rice University Science Masters’ Program board of Affiliates, is a founding member of Industry-Rice Earth Science Symposium initiative, was a director for the Alliance for Marine Remote Sensing, and was a director of the Geosat Committee, Inc. He has broad interest in the physics, environmental and Earth sciences and has made contributions in medical physics
Jeffery B. Thurston received his BS (1998) from the University of Alberta in physics and an MS (1991) in geophysics. He worked at Home Oil Co. Ltd., the LITHOPROBE Seismic Processing Facility, and Commonwealth Geophysical Development Co., Ltd., before joining Geoterrex in 1994. His interests include algorithm development and applications for mapping with geophysical data. He is a member of APPEGA and SEG. Jeffrey B. Thurston and Richard S. Smith received the 1997 SEG Best Paper in Geophysics Award for their paper Automatic conversion of magnetic data to depth, dip, and susceptibility contrast using the SPI (TM)! Method.
Clive Foss is a potential field geophysicist with particular interest in the magnetic field expression of remanent magnetisation. Clive received his BSc in geological geophysics at Reading University and a PhD at Leeds University in palaeomagnetic studies. Clive is now a Senior Geoscientist with CSIRO Earth Science and Engineering.
Jeffrey B. Thurston and Richard S. Smith ‘Automatic conversion of magnetic data to depth, dip, and susceptibility contrastusing the SPI (TM) method’ GEOPHYSICS, VOL. 62, NO. 3 (MAY-JUNE 1997); P. 807-813,4 FIGS
Alan B. Reid and Jeffrey B. Thurston ‘The structural index in gravity and magnetic interpretation: Errors, uses, and abuses’ GEOPHYSICS, VOL. 79, NO. 4 (JULY-AUGUST 2014); P. J61–J66, 3 FIGS., 1 TABLE. 10.1190/GEO2013-0235.1
Desmond FitzGerald, Alan Reid, Philip McInerney, ‘New discrimination techniques for Euler deconvolution’ Computers & Geosciences 30 (2004) 461–469
Jeffrey B. Thurston, Richard S. Smith, and Jean-Claude Guillon, ‘A multimodel method for depth estimation from magnetic data’, GEOPHYSICS, VOL. 67. NO. 2 (MARCH-APRIL 2002); P. SSS-S61,6 FIGS., 1 TABLE. 10.1 lSH)/l. I468616