National

Title and Summary:

Grayscale representative elementary volumes: An innovative approach to investigate pore-scale REVs from raw micro-CT images

Representative Elementary Volumes (REVs) are at the foundation of measuring rock properties that capture local heterogeneities of the rock structure at a particular length-scale for upscaling purposes. High-resolution micro-computed tomography (micro-CT) images of rocks have allowed a full 3D characterization of rock structures at pore-scale. These micro-CT images store information about rock structure as variations in the gray-level intensities or CT numbers. However, the direct use of these information-rich raw micro-CT images for rock characterization has not been possible due to a limited number of rock properties that can be calculated from them. In this study, we implement a novel texture characterization technique called the Gray-level Size Zone Matrix (GLSZM) to analyze the raw micro-CT images. We apply the GLSZM approach to homogeneous and heterogeneous sandstones and carbonates and show that this method highlights important rock features such as mineralogical heterogeneities and sub-resolution porosity. Considering these features, we calculate GLSZM statistics, that serve as proxies to porosity and permeability, which are crucial petrophysical properties. Comparing the trends of these proxies to petrophysical properties at various scales and spatial locations of the rock sample, we then infer Grayscale REVs (GREVs) and validate it using existing literature. Finally, we show that using the GLSZM-based approach, we can infer GREVs in a robust, reproducible, and fast manner. These GREVs can then serve as a priori for further petrophysical characterization of rock samples. 

Bio:

Ankita Singh is a Ph.D. student at the School of Minerals and Energy Resources Engineering at UNSW, Sydney. Her work focusses on implementing texture analysis techniques for rock characterization by directly using raw x-ray images. Her Ph.D. work has been published in reputed journals such as Water Resources Research and Geophysical Research Letters. She also won the 'Best Engineering/Environmental Student Paper' at AEGC 2019 in Perth and was the 2019 Finalist at the UNSW Three Minute Thesis Competition. 

Register now: https://us02web.zoom.us/webinar/register/WN_gYxzak7oQ_y6-AE_JwdXEQ

A new ASEG webinar brought to you by FedEx on Tuesday 25 August, 2:30pm (AEST) for a talk by Meghan Miller.

On the cusp of a tear:  continental subduction in the Banda arc

Eastward along the Sunda-Banda arc, convergence transitions from subduction of oceanic lithosphere to arc-continent collision. This region of eastern Indonesia and Timor-Leste provides an opportunity for unraveling the processes that occur during collision between a continent and a volcanic arc, and can be viewed as the temporal transition of the process of continental collision along strike.  We have collected a range of geological, geodetic, seismic, and geomorphic data to place constraints on the geometry and history of subduction. Utilizing ~4 years of new broadband seismic data we image the structure of the crust through to the mantle. Ambient noise tomography of the crust shows velocity anomalies along strike and across the arc, related to structure of the incoming Australian plate. The pattern of anomalies at depth resemble the system of salients and embayments that are present offshore western Australia, which formed during rifting of east Gondwana. At mantle depths, transition from oceanic subduction to continental collision appears reflected in new teleseismic based images, coinciding with previously identified changes in the geochemistry of the arc volcanics. Results from our body wave tomography show continuity of the subducting slab to depths of at least 300 km, with no evidence for tearing at the scale of >~50 km even in the region of arc-continent collision. Our expanded catalogue of Benioff zone seismicity reveals earthquakes in what was previously thought to be a seismic gap (the Wetar gap). Together, our seismic results suggest that tearing is not as advanced in this region as previously hypothesized, implying sustained subduction of continental lithosphere underneath the Banda arc. We suggest the tectonic evolution of this region is defined by inherited structure of the Gondwana rifted continental margin of the incoming plate.  Altogether, we suggest that this region is characterized by subduction of continental lithosphere poised for tearing that has perhaps just initiated, but with no large slab windows. Therefore, the initial template of plate structure controls orogenesis and deep mantle structure.

Register now: https://us02web.zoom.us/webinar/register/WN_MQI0S4DfQnyKG1hzAzoVYA

A new ASEG webinar brought to you by FedEx on Wednesday 9 September, 3pm (AEST) for a talk by Dr Alison Kirkby, Geoscience Australia.

AusLAMP in the Tasmanides: Lithospheric architecture and mineral potential from magnetotellurics

This presentation will showcase a recently released resistivity model of the southeast Australian lithosphere from Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) data collected over the last 7 years in collaborations between GA, GSNSW, GSV, GSSA and the University of Adelaide. For the first time, we image conductive regions at and below the base of the crust (>35 km depth) that may represent fossil fluid pathways along the Australian continental margin ~440 to 380 million years ago. The geometries of these conductive regions match those revealed in the upper crust by potential field and passive seismic data, and are a key part of crustal architecture predicted by the Lachlan Orocline model for the evolution of the southern Tasmanides. Conductive regions in the lower crust also correlate with known gold deposits, which may help to guide future mineral exploration in southeast Australia.

Register now: https://us02web.zoom.us/webinar/register/WN_tKJIKPMVQACF7sV7OQbYqw

The PPDM is holding its annual "Australian Petroleum Data Management conference" in a couple of weeks. The workshop will be held virtually, which allows the event to be within realistic reach of many more people than usual – hopefully all the people of the region who would be keen to attend some or all of it.  As an active member of both societies, I see member benefit in communicating this event to the  Petroleum and Minerals Exploration community of Australia at a discount: any member of the ASEG community who would like to attend either the workshop or the half day of short training courses is welcome to do so with a 25% discount on the already very low costs of attendance.

The workshop theme is "Navigating The Future of E&P Data Management Beyond 2020" and the workshop takes place on 2 successive half-days, on 26th and 27th August 2020.  Rock-bottom "early bird" rates available now.  Full details: https://lnkd.in/ebniq45.  Any question, anyone is welcome to contact me.

Prior to the workshop event is a half-day of short courses on August 25th to be delivered by North America-based experts:

1. Overview of the Open Subsurface Data Universe (OSDU) - Daniel Perna, EPAM Systems, USA

2. Introduction to Machine Learning - Lewis Matthews, West Texas Data Science Institute, USA

3. Introduction to Data Governance - Kevin Brunel, Brunel Analytics, USA
A half-day program at a low cost (very low for "early birds", available now).  Tuesday, August 25, 2020 (Australia Time), available online to all interested, anywhere.  Full details: https://lnkd.in/e-bvUJj.

For more information adn the discount details, please view the flyer here.

We are also happy to announce another new webinar by the NSW branch of ASEG on Wednesday 19 August, 6pm (AEST) for a talk by Bob Musgrave, Geological Survey of NSW.

State of the Arc: Long-Wavelength Geophysics and Macquarie Arc Basement

The Ordovician Macquarie Arc is the host of world-class Cu-Au mineralisation. But what lies beneath: sea-floor, thinned continent, or an older arc? Long-wavelength magnetic, gravity, MT and seismic features are the key to reconciling tectonic models, geochemistry, and geochronology of the arc.

Register now: https://us02web.zoom.us/webinar/register/WN_Sj1imrBlTCelHQELbEiwjA

Geoscience Society/AGC – Webinar: Iron-Oxide Copper-Gold (IOCG) Deposits: Definition, Nature, Tectonic Setting and Magmatic-Hydrothermal Origin

Participants will gain an insight into the iron oxide-copper-gold (IOCG) group of deposits, discussing the temporal distribution and tectonic environments of the various subtypes.

Date: Tuesday 11th August 2020

Time: 5.00 pm – 6.00 pm AWST

Presenter: Professor David I Groves – Recipient of AGC’s National Geoscience Champion Award in 2018

Cost:

AusIMM Member – Free

Member of an AGC Member Society (AIG, GSA, ASEG etc.) – Free

Non Member – $20.00

To register, go to this link

Digital Tech Talk Overview

This talk has a closer look at iron oxide-copper-gold (IOCG) group of deposits, discussing the temporal distribution and tectonic environments of the various subtypes. The sub-classes include low-Ti iron oxide-associated deposits that include iron oxide (P), iron oxide (F, REE), skarn Fe or Cu-Au and high-grade Au ± Cu.

It appears most likely that formation and preservation of giant IOCG deposits was largely a Precambrian phenomenon related to heightened activity of mantle plumes that impacted on buoyant  metasomatized SCLM at that stage in Earth history, with Phanerozoic IOCG deposits forming only rarely in tectonic settings where conditions similar to those in the Precambrian were replicated.

Presenter Bio

David Groves was born in Brighton, England, and migrated to Tasmania where he was educated at Hobart High School and at the University of Tasmania, completing a PhD on the giant Mt Bischoff tin deposit under the mentorship of Mike Solomon. After a period with the Geological Survey of Tasmania, where he learned mapping and field skills, David was appointed Lecturer in Economic Geology at the University of Western Australia (UWA) in 1972. In 1987, he was awarded a Personal Chair at UWA and formed the Centre for Strategic Mineral Deposits, which morphed into the Centre for Global Metallogeny, with him as Director, and which became the Centre for Exploration Targeting after his retirement as Emeritus Professor. He had a very successful academic career in terms of approximately 500 highly-cited published papers and book chapters, many keynote and invited lectures, and mentorship of many outstanding postgraduates, being awarded 12 medals and prizes, including the SEG Silver and Penrose Gold Medals and the SGA-Newmont Gold Medal, and being inducted into the Australian Academy of Sciences as a Fellow. He has been President of GSA, SEG and SGA during his career and represented Australia on UNESCO committees.

https://events.csiro.au/Events/2020/July/10/Our-Knowledge-Our-Way-Launch?

Online virtual event

To join us, please register by clicking ‘Register now’ below. You will receive a confirmation email with further information.

Indigenous-led approaches to strengthening and sharing our knowledge for land and sea management, Best Practice Guidelines from Australian experiences.

About the event

The launch will feature a short film, followed by a Q&A session with Indigenous co-authors and partners.

With contributions from over 100 Indigenous individuals and organisations, these Indigenous-led Guidelines support a step-change in learning, by both Indigenous peoples and their partners, about best practice ways of working with Indigenous knowledge to look after land and sea Country.

Supported by NAILSMA and CSIRO, the Our Knowledge Our Way Guidelines are based on 23 case studies that illustrate the critical principle that Indigenous people must decide what is best practice when working with their knowledge.

Join us for our Online virtual event

Please click Register Now
to join us

Webinar details:

Wednesday August 12th is available for a live webinar. 

12.30 - 2.30pm AEST (10.30am - 12.30pm AST)  

Registration at the following link. https://tas.currinda.com/register/event/2134

Imposter Syndrome/ Inner critic workshop

Have you felt like a ‘fake’ and some point in your career? Have you questioned why people should listen to you when presenting? Have you worried you may be ‘found out’? Or, has a nagging voice in your head told you that it was ‘luck’ which awarded you the position you are in now? Well, you’re not alone. Up to 70% of people are likely to experience ‘impostor’ like symptoms in some capacity in our careers. In this practical and interactive session, learn the four critical elements to working with your Inner Critic, identify how to work collaboratively with limiting beliefs which may also limit your success; and learn practical tactics you can implement to influence your next steps.

Title: End-to-end seismic inversion of geostatistically complex reservoir facies models with deep convolutional neural networks

Anshuman Pradhan, Stanford University

Date & Time: 6th August 2020; 12 – 1PM AWST

https://us02web.zoom.us/webinar/register/WN_-3DqbXyKRuuQL88cngGFBg

Summary:

We present a framework for performing end-to-end seismic inversion of reservoir facies models under complex geostatistical models of prior uncertainty. In our methodology, we directly learn the end-to-end inverse mapping between 3D seismic data and reservoir facies using deep 3D convolutional neural networks. Our training dataset is simulated from the forward generative model comprising of the geostatistical prior on facies and geophysical model relating seismic to facies through elastic properties. To ensure reliability during prediction with real data, a method for performing data-based falsification of prior uncertainty is presented. Using a real case study from an offshore deltaic reservoir, we demonstrate the efficacy of our approach by inverting a large-scale facies model from 3D post and partial stack seismic data.

Biography:

Anshuman Pradhan is a PhD candidate in the department of Energy Resources Engineering at Stanford University. He is a research assistant associated with the Stanford Center for Earth Resources Forecasting, Stanford Rock Physics and Borehole Geophysics project and the Stanford Basin and Petroleum System Modeling consortia. Anshuman obtained his M.S. and B.S. degrees in Applied Geophysics from Indian Institute of Technology (Indian School of Mines), Dhanbad, India. Anshuman has several industry and academic internship experiences where he has worked on applications related to reservoir modeling, seismic inversion and machine learning. 

Presenter: Alberto Ardid Segura

Date: 18th August 2020

Time: 1300 AEST

Title: Lithologically-constrained stochastic magnetotelluric inversion for imaging shallow conductors in geothermal fields

Abstract:

Geothermal fields are usually explored by magnetotelluric (MT) surveys primarily to characterize a shallow conductor reflective of a conductive clay structure, commonly known as the clay cap. Standard deterministic MT inversions suffer from non-uniqueness and uncertainty, and the inclusion of useful lithological information is still limited. We develop a Bayesian 1D inversion method that integrates the electrical resistivity distribution from MT surveys with Methylene Blue (MeB) data, an indicator of conductive clay distribution in geothermal wells. The inversion seeks to infer under uncertainty the shallow conductor boundaries in geothermal fields. By incorporating borehole information, our inversion reduces non-uniqueness and then explicitly represents the irreducible uncertainty as estimated depth intervals for clay cap boundaries. This is particularly important when constraining the lower conductor boundary, as this feature is difficult to discriminate from the MT alone.

We apply the methodology to a set of 250 MT stations and 130 MeB profiles in the New Zealand Wāirakei geothermal field to estimate under uncertainty the conductor boundaries. Then, we compare the infer boundaries with the clay distribution, temperature logs and lithology from wells to estimate temperature gradients and conductive heat flux through the clay cap. By quantitative correlations among the different data sets, we present an unprecedented view into clay capping structures in high-temperature liquid dominated geothermal fields.

Bio:

Alberto is a MSc geophysicist who studied at the University of Chile, and is a current Doctoral candidate at the Geothermal Institute in the University of Auckland. His doctoral research is focussed on studying the electrical resistivity distribution in geothermal fields through Bayesian magnetotelluric inversions that allows assimilating data from different properties such as lithology and temperature, and quantifying uncertainty. Prior to that, Alberto’s research focused on shallow active and passive seismic exploration on geothermal systems. He also has industry experience mostly related to R+D in direct current, gravity and magnetic geophysical methods for mining and basin research.

To register, please go to this link: https://us02web.zoom.us/webinar/register/WN_qDrzV7GsQOKBtCnBApxeBQ