ASEG Victoria - Technical Meeting Night and Annual General Meeting

Dear valued ASEG Victoria member

You are invited to the next technical meeting night to hear Mr. Rod Paterson (Principal Geoscientist, Intrepid Geophysics) present on Tuesday 16th of April from 6pm at The Kelvin Club.

The presentation will be preceded by the Annual General Meeting of Members of ASEG Victoria, but first…

2.5D forward modelling has been completed on a series of synthetic electrical property models to evaluate and compare the responses of the 25Hz Tempest, 25Hz VTEMplus and 12.5 and 6.25Hz HeliTEM2 systems to a large tabular conductor buried between 30 and 430m below 30m of conductive cover with and without

chargeable IP properties. The response to a surface SPM layer above the conductive cover or at surface in the resistive host is also modelled and compared.

The properties chosen to populate the model are representative of environments encountered in recently inverted surveys for these systems. The model results show that as the waveform turnoff sharpens and the system frequency decreases the sensitivity to shallow near surface IP effects increases dramatically and suggests that in this environment common in Australia and other deeply weathered regions in Africa, the benefits of using these systems to detect deeper and more subtle conductors are not being realised.

A selection of the model results was inverted using the Moksha 2.5D inductive only and the joint inductive and IP inversion methods to determine if these complex models are accurately recovered. The results indicate that it is very difficult or nearly impossible to recover the original geoelectric section when IP dominates the inductive signal in this way.

Speaker bio:

Rod is a multiskilled geoscientist with +50 years’ experience in the application of geology, geochemistry and geophysics in mineral and petroleum exploration. He spent the first two decades working as a geologist for Aberfoyle/Cominco in mineral exploration and mining with emphasis on tin and VMS deposits in NSW and Tasmania. Rod worked as a mine geologist and ore resource specialist during that period and later worked on introduction of software applications for image processing of geophysics, geochemistry and remote sensing data to exploration programs.

From 2003, he worked for 4 years in BHP Billiton Falcon Operations working as a Gravity Gradiometry and Magnetics processor. Concurrently developed automated QC processes and workflows and later managed the data processing group. In 2007, Rod joined Intrepid Geophysics in a Software Testing and Gatekeeping role. The job evolved into software training and course development and data processing and service work this included Gravity/FTG/Mag/Rad QC and reprocessing and 3D Geological modelling and Magnetic and Gravity inversion.

The past 8 years have been focussed first on the development/testing of 2.5D electromagnetic inversion software with Jovan Silic which is integrated into Intrepid's GeoModeller software. Then later running Intrepid's 2.5D AEM inversion service which commenced in 2016. To date Intrepid Geophysics have inverted ~300,000 line kms worldwide, ~50% in Australia and ~25% Southern Africa.

Note: light refreshments will be provided on the night.

**Notice of Meeting**

Members of the Australian Society of Exploration Geophysicists are advised that a general meeting of members of the Victoria Branch will take place as follows:

Time: 6:40pm

Date: Tuesday 16th April

Place: The Kelvin Club, 14-30 Melbourne Pl, Melbourne VIC 3000

Agenda: Election of Officers

Nominee for role of Branch President – Dr. Mark McLean

Nominee for role of Branch Secretary – Mr. Tom McNamara

Re-election of Branch Treasurer – Dr. Jarrod Dunne

Event Venue & Nearby Stays

The Kelvin Club, 14-30 Melbourne Place, Melbourne, Australia