SA

Alison Kirkby: Integration of seismic, magnetotelluric and magnetic data to reveal crustal structure in the Arunta region, Central Australia

This presentation will show results from recent 3D inversions of magnetotelluric data along the 09GA-GA1 deep magnetotelluric and seismic reflection transect. The data were acquired from 39 broadband and 18 long period stations. The broadband data have been reprocessed, yielding an extended bandwidth of 0.004 to 1300 s. A 3D isotropic resistivity model provides a good fit to the data; however the presence of off-profile features with a similar spacing to the stations may suggest the presence of anisotropy in the Irindina Province. The resistivity model indicates at lying structure in the Davenport Province and overlying Georgina Basin, which contrasts with a tendency toward sub-vertical structure in the Aileron Province in the southern half of the line. Conductivity anomalies in the Aileron Province coincide with peaks in magnetic susceptibility as defined by inversions of Total Magnetic Intensity data, and are therefore interpreted in terms of a magnetic alteration mineral such as magnetite or an iron sulphide.

Biography

Alison joined Geoscience Australia in 2008 after completing her MSc in Geology at the University of Auckland. She worked in the Geothermal Section at GA until 2013. In 2013, she commenced a PhD at the University of Adelaide with Graham Heinson, looking at the resistivity characteristics of fractured rocks. After completing her PhD in 2016, she joined the MT and Seismic section at GA. Her current work involves developing the MTPy software package for MT data analysis, and the modelling and interpretation of new MT datasets.

The SA/NT Branch is holding a Spring Fling

A night of Drinks, Nibbles and Conversation jointly presented with PESA, The Young Petroleum Professionals, the SPE and the ASEG.

The cost is $10 per head.

RSVP to Lewis.Maxwell@santos.com by 21 st September.

RiAus present Scinema

Join us for the largest science film festival in the southern hemisphere, the SCINEMA International Science Film Festival presented by Australia's Science Channel, RiAus.

We will be screening a compilation of short films on Numbers and Data (program below), recommended for those curious to see how numbers and data shape our culture and drive our decisions.

Everyone is welcome to this event, hosted by the SA/NT branch of the Australian Society of Exploration Geophysicists (ASEG) at a cost of $10 pp includes film, beer, wine (for those 18 years+), softdrink, and pizza. Please arrive at 6 pm for pizza with the film starting at 6:30 pm.

Cost: $10 per person

Book through Eventbrite or by email to SA/NT Branch president.

Seismic Full Waveform Inversion for Fundamental Scientific and Industrial Problems.

Seismic waveform inversion is a powerful method used to quantify the elastic property of the subsurface. Although the development of seismic waveform inversion started in the early 1980s and was applied to solve scientific problems, it became popular in industry only about 15 years ago. One of the key elements in the success of seismic waveform inversion has been the increase of the acquisition of long offset seismic data from 3 km in the early 1990s to more than 15 km today. Not only did long offset data provide refraction arrivals, but it also allowed recording of wide-angle reflections, including critical angles, providing unique information about the subsurface geology.

In this talk, I will elaborate on the early development of the seismic full waveform inversion (FWI) and its application to solve fundamental scientific problems. The first big success of FWI was its application to gas hydrate reflections, also known as bottom simulating reflection (BSR), which showed that the
BSRs are mainly due the presence of a small amount of free methane gas, not a large amount of hydrates stored above the BSR, and hence the total amount of methane stored in marine sediments should be much less than previously estimated. A second major success of FWI was its application to quantify the characteristics of the axial melt lens observed beneath ocean spreading centers. The seismic full waveform inversion results show that one can distinguish between pure melt and partially molten mush within a 50 m thick melt lens, allowing to link the melt delivery from the mantle with the hydrothermal circulation on the seafloor. The application of full waveform inversion to spreading center problems has become an important area of research.

Unlike in sedimentary environment, the seafloor in general scientific environment could be very rough and water depth could be deep, making it very difficult to use the conventional method of background velocity estimation. To address this issue, the surface seismic data could be downward continued to the seafloor, as if both streamer and sources were placed on the seafloor, similar to land geometry. This method allows to bring the refraction starting from zero offset to far offset, which is extremely useful for full waveform inversion of first arrivals. The downward continuation also allows to reduce the seafloor diffraction, increase the moveout of reflection arrivals, and enhance wide-angle reflections, all important for seismic full waveform inversion. The application of a combination of downward continuation and FWI has allowed to quantify gas anomalies in sedimentary basins and fluids at subduction fronts. The waveform inversion also has been used to monitor CO 2 sequestration.

I will explain the intricacy of FWI, based on the physics of waves, specifically the role of amplitudes and converted waves in addressing fundamental scientific problems. The presentation should interest professionals working in the oil and gas sectors, or crustal studies and global seismology.

More details and biography.

'Next week we have a talk by visiting Senior Research Geoscientist Dr Clive Foss from CSIRO Mineral Resources, speaking about 'Paragon Bore – a special place in the South Australian magnetic field.'

This event will be held on Level 7 of 101 Grenfell St, Adelaide in Training Room 1 at 12 pm till 1 pm on Friday 6th July. Bring along a gold coin donation, with a light lunch provided.

Please send through an email to sa-ntpresident@aseg.org.au if you are thinking about coming along, to give us a rough idea of numbers for catering purposes. Don't forget to include any dietary requirements

Finding and exploiting correlations between 3D seismic, log, and engineering data using machine learning or

The future requirements of integrated E&P: Shallow learning – but deep thinking!

Kurt Marfurt's SEG DISC will tour Australia between 11 and 25 July. After each day-long course, Kurt will speak at selected branch technical nights. These talks may be attended by members and non-members alike as with any technical night.

Please check this page for updates on course locations and times in your city. Some of these talks will talk place over lunch.

The day-long course is aimed at:

• Seismic interpreters who want to extract more information from their data.
• Seismic processors and imagers who want to learn how their efforts impact subtle stratigraphic and fracture plays.
• Sedimentologists, stratigraphers, and structural geologists who use large 3D seismic volumes to interpret their plays within a regional, basin-wide context.
• Reservoir engineers whose work is based on detailed 3D reservoir models and whose data are used to calibrate indirect measures of reservoir permeability.
• Team leaders who wish to identify advances in machine learning technology that promise improved efficiency and accuracy in the integration of large data volumes.

Kurt Marfurt's SEG DISC will tour Australia between 11 and 25 July using the schedule

Please check this page for updates on course locations in your city.

The course is aimed at:

• Seismic interpreters who want to extract more information from their data.
• Seismic processors and imagers who want to learn how their efforts impact subtle stratigraphic and fracture plays.
• Sedimentologists, stratigraphers, and structural geologists who use large 3D seismic volumes to interpret their plays within a regional, basin-wide context.
• Reservoir engineers whose work is based on detailed 3D reservoir models and whose data are used to calibrate indirect measures of reservoir permeability.
• Team leaders who wish to identify advances in machine learning technology that promise improved efficiency and accuracy in the integration of large data volumes.

More course details and registration here.

SEG DISC Lunch: Kurt Marfurt

Kurt will also be presenting to us a lunchtime talk titled “Finding and exploiting correlations between 3D seismic, log, and engineering data using machine learning
(The future requirements of integrated E&P: Shallow learning – but deep thinking!)” on Tuesday 17th July at the Hotel Tivoli at 265 Pirie St, Adelaide. Tickets are for sale through Eventbrite until Friday 6th July. Priced at $15 for students, $20 for ASEG members and $30 for non-members, tickets include a 2 course meal and bar tab.

Menu

• Entree: arancini balls with napoletana sauce (v)
• Main: alternate drop between 
  • Slow roasted beef fillet, served with roasted potatoes and seasonal vegetables & red wine jus (gf)
  • Crispy skin chicken breast, stuffed with garlic & herb butter served with asparagus and mashed potato (gf)).

Please arrive at 12pm with entrees served by 12:15pm and mains and Kurt’s talk to follow. with event concluding by 2pm. I hope to see you there for what I’m sure will be a wonderful talk and great food!

Title: Three-dimensional seismic imaging of shallow crustal volcanic plumbing systems

Presenter: Simon Holford
When: Wednesday, June 13th, 2018
Time: Drinks and food from 5:30 pm, presentation from 6:15 pm

Cost: Members: free, Non-members $10, Students: free
Where: Coopers Alehouse, 316 Pulteney St, Adelaide.

Abstract:

Developing a clear understanding of the movement of magma through Earth’s crust, where it is temporarily stored, to the surface where it erupts, is a grand challenge in the Earth Sciences. Detailed knowledge of the geometry and connectivity of the conduits and reservoirs (e.g. subsurface sheet intrusions such as sills, laccoliths and dykes) that form sub-volcanic plumbing systems (VPSs) is critical to understanding a range of fundamental, interdisciplinary research problems including continental breakup and the thermomechanical state of the mantle, the physiochemical evolution of magma and the forecasting of volcanic eruption dynamics. Addressing these problems is challenging because active VPSs are generally inaccessible. VPSs are traditionally viewed as comprising vertically stacked magma reservoirs linked by dykes, such that eruption sites of directly overlie the sources of melt generation in the upper mantle or lower crust. This presentation will show how the application of three-dimensional (3D) seismic reflection technology to permit the study of ancient, buried VPSs offshore Scotland and in the Great Australian Bight in unprecedented scale and detail, has challenged the traditional view of VPSs, suggesting that in certain cases, VPSs can be dominated by extensive, interconnected sill complexes that facilitate lateral upper crustal magma transport over distances of tens of km, in some cases leading to voluminous volcanic eruptions. It will also show how 3D seismic analysis of VPSs can help reduce exploration risk in energy-rich sedimentary basins.

Biography:

Simon Holford is an Associate Professor of Petroleum Geoscience at the Australian School of Petroleum. Prior to commencing an academic role at the University of Adelaide, Simon was an ARC Australian Postdoctoral Fellow. With Ros King, he jointly leads the Stress, Structure and Seismic Research Group. Simon has published over 80 papers on various aspects of sedimentary basin tectonics and petroleum geoscience. He is a past president of the SA/NT branch of the Petroleum Exploration Society of Australia.

Talk abstract

The marine seismic industry is constantly striving for greater efficiency in acquiring seismic data: the quicker a survey area can be acquired, the more competitive the cost to the customer. But acquiring large surveys with unconventional spreads can impose limitations on the recorded data, so that certain geophysical requirements for the exploration or development objectives may be compromised. This is especially the case in shallow water areas, where traditionally the width of the streamer spread is restricted in order to image the shallow section.

We will look at some modern acquisition approaches for towed streamer seismic currently offered in the industry; these are very different ideas, but each aims to provide increased cross-line density or improved acquisition efficiency, or indeed, both.

In particular, we will look at the use of multiple sources instead of the conventional dual-source configuration, the use of the cross-line component in multi-sensor recording, an approach based on compressive sensing, and an imaging approach that exploits free surface multiples to provide greater illumination of the near surface. For each

of these approaches we look at its value proposition and ask how well it stacks up to its promise, and what are, if any, the associated limitations and concerns regarding the resulting “data quality”?

Speaker biography

Maz Farouki has a BSc degree in physics from Manchester University and more than 40 years of industry experience with seismic contractors, mostly on overseas assignments. He has lived and worked in the United Kingdom, Zaire, Pakistan, Algeria, Egypt, the United States Australia, Norway, Singapore and Malaysia, holding technical and management positions in data processing, imaging, and marine geophysics. Most of his tenure has been with two employers: the Seismograph Service Companies from the late 1970s and Petroleum GeoServices (PGS) from the 1990s. For a number of years he specialized in velocity model building and depth imaging at a time when the discipline was in its infancy in the industry. His current position is geophysical advisor for PGS Asia Pacific Marine Contract based in Kuala Lumpur, Malaysia. He is an active member of SEG and EAGE and has received ‘best paper’ awards at industry regional conferences and workshops.

More information