Industry

Title: What we can and cannot know from unconstrained inversion of regional magnetic field data

Presenter: Clive Foss / CSIRO Mineral Resources

Date and time: 4pm (AEST time), 27th Sep 2023

Registration: https://us02web.zoom.us/webinar/register/WN_4o61GZALT9e7daAhyQKDzg#/registration

Abstract:

For many years regional magnetic field data acquired by Geoscience Australia and State and Territory geological surveys has enabled and transformed geological mapping across Australia where many areas are beneath extensive cover and/or pervasive deep weathering. As computing power and availability have increased by orders of magnitude the same data that so successfully supports geological mapping is being re-purposed for building continuous three-dimensional magnetisation models. These models are in some cases accepted by their users in confidence that they are true representations of the subsurface achieved by spectacular powers of computing. However, while aeromagnetic surveys perform extremely well in mapping the horizontal locations and extents of magnetisations, recovery of models of subsurface magnetisation is severely restricted by extensive non-uniqueness. Magnetic field data is so useful for geological mapping because of the dominant expression of shallow magnetisations, in many cases directly beneath a basement unconformity. The sharp curvature of these field variations carries all the reliable information in the magnetic field data. Deeper magnetisations may cause the bulk of amplitude changes in the magnetic field without giving rise to diagnostic curvature of the field. These parts of the magnetisation cannot be reliably assigned to a specific depth or depth range. In space-filling voxel inversions this task is achieved by depth-weighting functions included in the inversion algorithms. It is these functions, not the distribution of magnetisation in the ground, that determine the depth distribution of magnetisation in the models.

I propose separation of features of sharp curvature that carry the most reliable source information (that I term ‘sweet spots’) from the remaining, much less informative field variations. This results in subsurface models that are much sparser in their apparent level of detail. It may seem a negative message, but it is not, because the distilled information can be treated with much higher confidence than continuous models in which it is not clear which aspects can be trusted and which cannot. I use examples of Australian regional magnetic field data to demonstrate analysis and interpretation of sweet-spots suitable for estimation of depth to magnetisation and sweet-spots suitable for estimation of magnetisation direction.      

Biography

Clive is a senior principal research scientist in CSIRO Mineral Resources where he works mostly on magnetic field inversion and interpretation. He has a BSc and PhD from two Earth Science departments where he learnt to integrate studies of physics and geology. His particular interest since his PhD (a long time ago) on Archean rocks of Southern Africa is in the magnetic field expression of remanent magnetisation and how direction of magnetisation can be recovered from magnetic field data. After his PhD Clive taught exploration geophysics at the University of Malaya in Kuala Lumpur where living between the geographic and magnetic equators provoked an interest in low inclination magnetic fields. Clive then moved to Bandung to work for the Bureau of Mineral Resources (BMR, now Geoscience Australia) on the AIDAB funded Indonesia – Australia Geological Mapping Project in Kalimantan. Following that Clive returned to Kuala Lumpur to work as a consultant and for ARK Geophysics based in Kuala Lumpur providing services in gravity and magnetic methods for petroleum companies throughout Southeast Asia. In 1995 Clive moved to Sydney, Australia to work with Encom Technology both contributing to the ModelVision development team and acting as senior consultant on gravity and magnetic projects worldwide. In 2009 Clive moved to his present position in CSIRO. 

Title: Digital Rock Under Stress

Speaker: Professor Maxim Lebedev

Date and Time: 28 September 2023, 5:30 pm

Registration: https://www.eventbrite.com.au/e/aseg-wa-special-tech-night-by-prof-maxim-lebedev-tickets-692145885977

Abstract:

Modelling the physical properties of rocks based on microstructure derived from X-ray microtomographic images (known as digital rock physics) is an important technology in geophysical rock characterisation. However, these images are most commonly obtained at room pressure and temperature conditions. Consequently, most digital rock physics models are not representative of the rocks at depth.

Reservoir rocks are at such depth that they experience high stresses and temperatures. The thermodynamic properties of the fluids inside the reservoir are pressure and temperature-dependent; therefore, transport properties are also temperature and pressure dependent. Moreover, it is well established that elastic rock properties of rocks are strongly affected by stress and/or fluid distribution. Thus, to acquire realistic pore network structures and fluid distributions (including, but not limited to, residual saturation) and reliably estimate transport and elastic properties from micro images, rocks with fluids inside have to be imaged at reservoir pressure and temperature conditions.

In this lecture, we will discuss how to obtain 3D images under elevated temperature and stress conditions and the challenges with imaging and further image processing. Finally, we will provide some results to demonstrate how the microstructure of the rocks can be linked to the transport and elastic properties of rocks measured on bigger samples.

The lecture is useful to rock physicists, petrophysicists, and reservoir engineers.

Bio:

Maxim is a Professor at Edith Cowan University, Australia. Maxim was awarded BS, MS and PhD degrees from the Moscow Institute (State University) of Physics and Technology in Russia. He has over 30 years of research experience in physics, material science and rock physics, working at leading research organizations in Russia, Japan, New Zealand, and Australia. In 2007 he joined Curtin University, and during 16 years at this University, he built a rock physics laboratory from scratch and  became the head of the experimental rock physics program. Recently he moved to Edith Cowan University. He has published over 180 peer-reviewed journal papers and is the inventor of 11 international patents. His current research is focused on the properties of subsurface reservoir rocks and minerals, including elastic and unelastic properties of rocks at teleseismic, seismic and ultrasonic frequencies; digital rock physic; mechanical properties of rocks at microlevel (nanoindentation); direct observation of multiphase fluid distribution inside rocks at reservoir conditions (microCT).

We are delighted to share with you the details for an upcoming SEG Distinguished Instructor Short Course (DISC) being hosted by the ASEG. 

This course will be run virtually over two days. 

Who: Dr Mark E Willis, Chief Scientific Advisor of Borehole Seismics at Halliburton

What: Distributed acoustic sensing for seismic measurements – what geophysicists and engineers need to know - DISC course

Where: Virtually. There will be a streaming of the virtual course in Brisbane at Anglo-American office, Brisbane, QLD. Please contact Tim.Dean.Geo@gmail.com if you would like to join the streaming (ensuring that you also register for the virtual DISC)

When: September 12th and 13th 2023, 9am - 1pm ACST each day. 

Cost: $250 USD for SEG and ASEG members which includes access to software and a copy of the accompanying e-book. ASEG members need to use the code emailed to them, or contact secretary@aseg.org.au. Registration cost for non-members is $375 USD.

Register: Please register here by September 12th.

Course description: Geoscientists and engineers are very comfortable using seismic data sets acquired with geophones, hydrophones, and accelerometers because we have a long, well-defined set of standards for acquiring, processing, and interpreting them. However, distributed acoustic sensing (DAS) seismic measurements are rapidly augmenting, and in some cases replacing, the data from these conventional tools. Technologists are frequently unaccustomed to using DAS seismic data sets since it directly acquires relative strain or strain rate measurements and not the more familiar pressure, displacement, velocity, and acceleration data. There are also acquisition parameter selections that must be made to optimize the acquired data to accomplish the purpose of the seismic survey. This course is designed to build an intuition and understanding of the value, limitations, and applications of DAS seismic technology. In addition to the lecture and accompanying book, software will be provided, which will allow the student to interactively explore DAS seismic technology.

For more details visit Current DISC - SEG.

Title: Geophysics and Graphite - from Foe to Friend

Presenter: Barry Bourne

Date and time: 22/08/2023 at 1730

Location: The Shoe Bar and Cafe 376 - 420 Wellington Street Perth, WA 6050

Registration: https://www.eventbrite.com.au/e/aseg-wa-special-tech-night-by-barry-bourne-tickets-694459455927

Title: The Seven Deadly Sins Of Scale: Why Petrophysics + Structure + Mineralogy Can Solve The Scale Paradox.

Presenter: Jim Austin

Date & Time: Wednesday, 16th August 2023 at 1800

Registration: https://us02web.zoom.us/webinar/register/WN_kVfHg58_T8qjdHp1Og-3Gw

Abstract:

Prior to the last decade, Petrophysicists typically had access to contextual information on the geology, but that information was qualitative, and unreliable.  of non-contextual (cf. geochemistry, maths, statistics). The advent of quantitative methods for mapping mineralogy and rock texture on palaeomagnetic samples took petrophysics out of the dark ages. It provided quantitative geological information on mineralogy and rock texture, which in turn provide insights into a range of contextual constraints, including alteration, deformation and metamorphism. Quantitative mineralogy allows us to classify our petrophysical data accurately, this providing a framework to interrogate data meaningfully. Inversely, petrophysics provides a lens through which to convert mineralogy into physical properties, many of which (unlike mineralogy and geochemistry) are truly scalar. If we can convert mineralogy to physics, we can understand crustal architecture across scales. Whilst petrophysics is gradually becoming more widely used, physics can be complex, magnetic and conductivity in particular. In this talk, Jim will outline the Integrated Petrophysics approach, illustrate how to integrate and use the data, citing case histories on IOCG, Magnetite and Magmatic Nickel deposits across Australia. We’ll discuss seven of the most common traps which lead to misinterpretation.  

Bio:

Jim Austin occupies the core of a Venn diagram in which petrophysics, geophysics, structural geology, alteration and magmatic mineralogy, GIS and guitar overlap. He is focussed on dissecting the petrophysical and structural anatomy of ore deposits, to understand the interaction of structural controls on alteration.

Title: Precision Impulsive: A high-productivity land impulse source.

Presenter: William Davie

Date/Time: 17:15, 27th July 2023

Registration: here

Abstract:

Precision Impulse (PI), a seismic source development company, will describe an actuator that drives a versatile seismic source. The source is portable with low environmental impact.

A new high productivity mode could acquire high quality 2D or 3D surface seismic data to find and analyze CO2 storage sites and critical minerals at lower cost with better logistics. The source can also be deployed to acquire 4D seismic data to monitor CO2 storage sites to prove integrity and to optimize geothermal energy production.

Bio:

An electrical engineer with more than 35 years’ experience in the global oil and gas industry, Will Davie began his career at SLB in North Africa, including introducing early versions of wireline conveyed borehole seismic. In most areas this involved putting an airgun in a pit filled with water, a bit tricky in the desert, hence his interest in an easier to deploy seismic source.

Following operational, technical and marketing roles, Will was appointed as Chief Economist to look at how better understanding of the subsurface can be used to provide more reliable, affordable energy with lower environmental impact. This included the formation of groups to look at CCS monitoring and applications of better subsurface understanding to Water management.

Will has been working on the new seismic source with Precision Impulse since 2012.

Title: A seismic source field trial in the Bass Strait: testing the impact of several different source configurations on geophysical quality, received sound and direct impact on scallops and lobsters

Presenter: Jon Cocker

Location: Ayre’s House, 288 North Tce, Adelaide

Date: Thursday 27th July

Time: 12 pm for a 12:30 pm start

Cost: ASEG members $60, Students $25, non-members $75

Please register for this event at: https://pesa.com.au/events/pesa-sa-nt-julytechnical-luncheon-a-seismic-source-field-trial-in-the-bass-strait-testing-the-impact-of-several-different-source-configurations-on-geophysical-quality-received-sound-and-di/?mc_cid=0b440b5b69&mc_eid=20402cfdd8

Overview:

Beach Energy acquired a seismic source technology field trial in Dec 2021 in the shallow waters (50-80m) of the Bass Strait. The trial consisted of eight source tests acquired along two 2D lines, including: a full-size array (2480 cu.in.) with Sercel G-GUN II in a wide-tow triple source configuration, eSourceTM (2098 & 1049 cu. in.), reduced size (300, 700 & 1260 cu.in.), and Distributed Source tests including Shearwaters Apparition test (140 & 340 cu.in.). A test of a 70 cu.in. airgun was also recorded during a whale mitigation procedure. The aim of the field trial is to investigate whether any of these source options:

1. Provide the required geophysical data quality

2. Significantly alter the received anthropogenic sound levels (SPL and SEL)

3. Changes the impacts on benthic invertebrates via analysis of scallop and lobster specimens placed on the seafloor

This combined data will then be used to determine if any of the alternative source options are suitable replacements for conventional full-sized arrays and if any provide a meaningful reduction to potential impact on marine organisms.

The study was performed in conjunction with the Institute for Marine & Antarctic Studies, Fisheries Research & Development Corporation, Curtin University, and the Department of Natural Resources & Environment Tasmania.

Scallop and lobster specimens as a model species for crustaceans and molluscs were placed on the seabed below the full array (triple and single source), both eSource arrays and one control location. The specimens were assessed over 6 months for physical damage, chronic effects and survival, pH, refractive index, total and differential haemocyte cell counts, DNA damage and biochemistry. Lobsters were also assessed for righting ability. The results will not be available until Q4 2023. Noise loggers were collocated with the specimens to measure received sound.

The data processing was completed by Shearwater. The results show that all options result in lower S/N raw shot gathers; but also, that modern processing algorithms are able to compensate for most of this through noise attenuation, deblending and designature. eSource (2098 and 1049 cu.in.) and the reduced source size options provide very similar final stack and migrated gather quality to the full array. Both apparition tests (140 & 340 cu.in.) were very similar in 2D stack quality but with slightly lower S/N below 4Hz and above 64Hz. The data quality of the other distributed source tests was better in the shallow but worse in the deep due to poor randomisation achieved. There are differences in gather quality that require further investigation. These results demonstrate that alternative sources and/or smaller volumes have the potential to meet survey objectives whilst reducing impact on marine life.

Bio:

Jon Cocker has been the Manager of Geophysics at Beach Energy since 2019. Prior to that he has held numerous other positions including Chief Geophysicist at DownUnder GeoSolutions and Seismic Acquisition R&D Team Leader at Chevron USA.

The WA Branch of the Australian Society of Exploration Geophysicist invites members and non-members to quickly rsvp for the special talk scheduled as:

Date:      Thursday, July 27, 2023
Time:      5:30pm (AWST)
Location: The Shoe Bar and Cafe 
               376 - 420 Wellington Street Perth, WA 6050
Parking: CPP parking is close by for those of you who will be driving to the city. 

Registration: Here

Bio:

James (Jim) Dirstein studied Geology and Geophysics at the University of Toronto. For more than 40 years he has enjoyed working as a geophysicist on many resource projects in Australia and overseas. In addition to his project work, Jim has played a role in the commercialization of several transformative technologies. During his career, these efforts   have involved working as an early adopter, angel investor or collaborator, in the fields of time series analysis, digital surface analysis along with a patented airborne acquisition system and a fully trained and patented Artificial Intelligence (AI). Outside of the realm of geophysics Jim has presented papers at metallurgy conferences on the role of microbes for in-situ mining, minesite remediation, Carbon capture and using microbes for permeability enhancement and the production of Hydrogen.

Abstract: 

The art of data interpretation is about finding patterns in data. Finding patterns requires careful observations. Human beings are very much visual creatures with our perception of the world based upon what we can see. Unfortunately, traditional interpretation methods are often biased by our senses as well as pre-existing ideas. Therefore, the combination of confirmation bias, along with things we “don’t see” distorts our perception of reality. Often data we are tasked with interpreting is presented to us a surface. This surface could be a digital elevation map or more likely data from remote sensing methods such as Potential Fields, Radiometrics or Seismic attributes, etc. As geoscientists we are always looking for ways that help us to organise information into more meaningful formats, enabling both accurate and time efficient reviews of data. Moreover, since most of interpretation of the geophysical data we acquire is non-unique in nature, we need to consider workflows to help minimise this non-uniqueness.
 

Since a fundamental property of any surface is its geometric characteristics, the identification and extraction of these properties can reveal features and objects not easily identifiable by visual analysis alone. In 2013, a new method for digital surface analysis was introduced to address some of the limitations of traditional surface analysis methods. This mathematical solution applies a completely different approach without the use of existing techniques or algorithms. With this method, the analysis of a digital surface involves the calculation of a complete set of morphometric properties as it is defined by differential geometry (e.g. Dupin Indicatrix). The resulting database of geometric elements is queryable using a GIS style interface providing an attractive means to simplify and accelerate the data mining process.
 

This analysis technique was introduced to the ASEG at the 23rd International Conference and Exhibition, 11-14 August 2013 Melbourne, Australia. The presentation and extended abstract was entitled “Digital surface Analysis: -A new approach using differential geometry”.

While the 2013 publication provided background and several examples, our evening presentation will discuss several new examples and workflows from our use of this technology over the last decade.

Drinks and nibbles will be available from 5:30pm - 6:15pm. The talk will commence promptly at 6:15pm. The ASEG WA thanks our sponsors for their continued support.

Please contact wapresident@aseg.org.au with any queries.

Title: Scalable Streamlining of Ambient Noise Tomography: A Simple Automated Approach for Dispersion Curve Estimation and Quality Control in the Era of Big Data

Speaker: Babak Hejrani

Date/Time: Jul 20, 2023 16:00

Bio:

Babak Hejrani is a seismologist specializing in the field of geophysics within GA's Onshore Seismic and Magnetotelluric Section. With a decade-long background as a researcher in academia, Babak joined GA in 2018 and has since made contributions to developing new technologies for passive seismic imaging. He has established fruitful collaborations with international organizations in Europe, Asia and Australia with a primary focus around developing and implementing advanced imaging technologies that provide enhanced insights into the lithospheric structure of Australia. Babak strives to push the boundaries of seismic imaging, enabling more accurate interpretations of subsurface features.

Teams meeting:

We are delighted to announce that CAGE is back for 2023!

The Australian Society of Exploration Geophysics is hosting a one-week Camp for Applied Geophysics Excellence in Western Australia from Sunday 24th of September, returning on Sunday October 1st, 2023. This field camp will involve seven days of real-world application of major geophysical techniques.

The camp kicks off with an introduction to the approaches, goals and challenges of geophysics for mineral exploration. The necessary field training, theory and methodologies of major geophysical techniques will be provided by industry-recognized experts. Potential field, electrical, electromagnetic and seismic methods will be explained, together with their applications for mineral exploration, natural resource management and geotechnical work. The deployment of geophysical equipment, work health and safety considerations and survey design will also be covered.

Participants will learn how to process geophysical data and utilise various commercial and open-source software packages. They will complete practical sessions on basic data importation and reduction, filtering, modelling, inversion, data display and importantly, interpretation. The camp also covers how to integrate diverse geophysical datasets to map/image the sub-surface in the vicinity of a sulfide target in Forrestania, Western Australia.

Attendance cost is fully covered by our sponsors and there are limited spaces available. Applicant selection will be based on the answers provided in these forms. 

Please fill out the expression of interest form below BEFORE June 26th for a chance to be selected for this amazing opportunity! 

https://shorturl.at/cnAGT.

Successful applicants will be notified by July 8th.

If your company is interested in sponsoring or providing in-kind support for CAGE 2023, please get in touch to find out more or for a copy of our sponsorship packages.

For any queries please contact continuingeducation@aseg.org.au

Key contacts are:

Kate Brand - ASEG Professional Development Chair 

Kate Selway - CAGE coordinator

Sasha Aivazpourporgou - CAGE logistics coordinator