January 2016 Technical Talk

BCGS Technical Talk – January 20, 2016

Speaker: Ross Polutnik, SJ Geophysics Ltd.

Title: Advances in 3DIP Array Design: Characteristics of Customizable Distributed Arrays

Date/Time: Wednesday January 20, 2016 @ 4:30pm

Location: 4th Floor Conference Room, Room 451, 409 Granville St. (UK Building at Granville and Hastings), Vancouver


Advances in 3DIP Array Design: Characteristics of Customizable Distributed Arrays
Syd Visser, Ross Polutnik, SJ Geophysics Ltd., Delta, Canada

Since the early 90’s, SJ Geophysics has been continually developing and experimenting with unconventional IP array designs. Current customized arrays utilized with the Volterra acquisition system make use of cross-line dipoles to improve the azimuthal distribution of the data. A key aspect of any IP survey, the selected array design must meet the survey objectives determined at the start of the project.In the mineral exploration industry, survey design rarely gets the time and attention that it deserves. Rather, surveys are acquired by essentially “shooting in the dark” using last week’s parameters in the hopes that the target of interest will become illuminated and the picture more clear. Unfortunately, this approach simply doesn’t work. A well defined survey objective and a-priori geologic information must be taken into consideration during the survey evaluation and design process in order to get the best results.

All to often the survey objectives are overlooked by the potential client when requesting a survey and replaced with “How deep can I see?” Their hope is to have an answer in 30 seconds. In trying to answer this question for clients, the importance of good array design becomes important.

Simple 2D-inline arrays have evolved into complex customizable arrays such as the diamond array that incorporate dipoles in multiple directions to maximize signal coupling and improve surface resolution.  An examination of receiver arrays and how they affect the resulting data collected will be discussed. Data examples from real world surveys will be provided to illustrate the benefits of 3DIP array designs. A key example is the Ootsa Property, owned by Gold Reach Resources. In 2013, SJ Geophysics took the initiative to re-survey the Seel deposit to compare their new 3DIP acquisition equipment and survey methods against an older IP survey acquired using conventional 2DIP and early 3DIP systems. The benefits of advanced 3D array designs is evident in the resulting inversion models.

December 2015 Technical Talk

BCGS Technical Talk – December 17, 2015

Speaker: Philippe Martin (Eng.), Senior Geophysicist
Golder Associates Ltd.

Title: Operational Geophysics at Collahuasi Mine, Chile

Date/Time: Thursday, December 17, 2015 @ 4:30pm

Location: 4th Floor Conference Room, Room 451, 409 Granville St. (UK Building at Granville and Hastings), Vancouver


Operational Geophysics at Collahuasi Mine, Chile.
Philippe Martin (Eng.), Senior Geophysicist, Golder Associates Ltd., Vancouver, Canada

The Collahuasi Mine is located at 4,800 meters above sea level on the Andean Plateau in the Tarapaca Region of northern Chile. Commercial activity at the mine dates back to 1880 when its systems of high-grade copper and silver veins began to be exploited. These operations continued for fifty years until their interruption by the Great Depression. Work in the area resumed in 1978 when key components of the Rosario deposit were identified. Although the layout of many of the abandoned tunnels and stopes are relatively well documented by Collahuasi, confirmatory drilling showed that the information from historical records is neither exhaustive nor always complete (the result of lost or forgotten records). Because of the transit of heavy machinery, these conditions are a cause of concern for the continued safe conduct of today’s operations. In addition, these cavities must be taken into account when a mine block is designed for blasting/exploitation, since they may noticeably decrease the ore grade of the block.

Over the course of the past 3 years, Golder Associates and Collahuasi have worked closely together to developed a quick and reliable method for detecting potential underground voids/abandoned tunnels at the site. The method uses high resolution 3D electrical resistivity imaging (ERI), microgravity and GPR, in combination with systematic confirmatory drilling of anomalies to achieve a rate of success of nearly 70% in voids detect.

As a separate topic, if time allows, we will also look at the results of a non-conventional approach used at Collahuasi for blast damage characterization of the rock mass using borehole geophysical techniques.

November 2015 Technical Talk

BCGS Technical Talk – November 19, 2015

Speaker: Willem de Beer, Principal, Golder Associates

Title: Automatic microseismic data processing using open source algorithms

Date/Time: Thursday, November 19, 2015 @ 4:30 pm

Location: Room 451, 409 Granville St (UK Building at Granville and Hastings), Vancouver


Over the last five years we have compiled a more or less coherent collection of scripts, a toolbox we call μQuake (microQuake) which enables us to efficiently, accurately and automatically, process seismic data. We believe that the field of “mine seismology” would benefit from having standardized, rigorously peer-reviewed tools. If these tools are open source, it reduces the “friction” slowing innovation considerably, as they can quickly be adapted and disseminated by and among mines, researchers and developers. In this talk we will study the performance of an open source library of microseismic data processing techniques based on programs routinely used by the earthquake community and released under permissive open source licenses, permitting event detection and association, P- and S-wave arrival time picking, event location in arbitrarily complex 3D velocity structures, source parameter characterization and advanced analysis.  We show the ability of the system to automatically process a data set collected in 2004 at Northparkes Mines E26 Lift 2 and compare the results to high quality manual processing, showing that the results are of similar if not better quality.

About the Authors:

Willem de Beer is a Principal of Golder Associates and a mathematical physicist with an innovation bug and a passion for applying esoteric concepts in mathematics and physics to practical problems. However, all analysis is critically dependent on data integrity, quantity and density, and therefore he learnt to design and implement industrially robust monitoring systems to deliver continuous and consistent data streams. He has  been back-analyzing and thinking about the rock mass response to mining over the last 17 years, using a variety of techniques from stock-in-trade statistical tools to sophisticated inversion and clustering methods. The one constant, though, in all the studies, is that it always starts with validating the data and ends with robust review by his rock mechanical engineering colleagues. He is a proponent of “design-as-you-mine” using real-time, online geotechnical and geophysical data streams and he designs systems to enable this. He has worked in South Africa, Australia, New Zealand, South America and North America.

Jean-Philippe Mercier is co-owner of Advanced GeoScience Imaging Solutions (AGSIS) and until recently was the Golder lead seismologist. He currently focuses primarily on mine seismology in the context of deep and high stress mining. Jean-Philippe’s main interest consists in developing processing techniques and monitoring approaches to exploit the untapped potential of seismological analysis in extracting information on the spatial and temporal response of the rock mass to mining. Dr Mercier earned a Ph.D. from UBC in crustal seismology and has co-authored multiple papers published in peer-reviewed journal and conference proceedings. He is the principal force behind, and developer of, the techniques presented today.

BCGS EM Workshop 2015 – Registration Now Open!

The BCGS Executive is pleased to announce that registration is now open for the fall 2015 EM Workshop.

When: Friday October 16, 2015

Where: BCIT Downtown Campus (555 Seymour St. Vancouver, BC)

Time: 8:00 am – 4:45 pm (PST)

Cost: Regular $120 / Student $60

Please register in advance of the workshop. Your registration can only be guaranteed once payment has been received. The attendee name must be entered for registration to be complete.

Payment will be accepted through PayPal. Click on the “Buy Now” button below.

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The BCGS Executive

BCGS EM Workshop 2015

The BCGS is proud to announce its EM Workshop 2015 that will be held at the BCIT Downtown Campus on Friday October 16th. The executive has been hard at work gathering an amazing panel of EM inversion experts who will discuss the latest advances in EM geophysics.
We are putting a slightly different twist on the workshop concept this year as it is going to be an e-poster type, day-long session, where our different experts will be presenting the best of their practical results, rather than a more formal presentation format. The day will start with our opening keynote speaker, Richard Smith, who will give an overview of all the different EM inversion procedures. Then attendees will be divided in small groups and will rotate through the presentations throughout the day. The small size of the groups is aimed at fostering discussion with our speakers and emphasizing the audience participation. At the end of the e-poster session our closing keynote speaker, Alan Jones, will wrap up the day by reviewing what was presented to the audience and what was learned during the day. Everybody will be then invited to join our speakers and the BCGS executive for a social event in a nearby location.

You can find below more details about the event, our sponsors and our speakers.Hope to see you all in October!


The BCGS Executive

Workshop Details

Opening Speaker: Richard Smith Laurentian University
Speakers: Dima Amine Geosoft Inc.
Lief Cox TechnoImaging LLC
Colin Farquharson Memorial University of Newfoundland
Peter Fullagar FGCL Consulting Ltd.
Eldad Haber University of British Columbia
Michal Kolaj Laurentian University
Doug Oldenburg University of British Columbia
Bill Petrick Industrial Imaging Co., Inc.
Phil Wannamaker University of Utah
Closing Speaker: Alan Jones Dublin Institute of Advanced Studies

Date: Friday, October 16, 2015

Time: 8:00 am PST – 4:45 pm PST

Location: BCIT Downtown Campus (555 Seymour St. Vancouver, BC, V6B 3H6, Canada

Admission Cost: Regular $120 / Student $60



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If you would like to sponsor our event, please contact us at info@bcgsonline.org

Speaker Bios

Richard Smith:  Laurentian University

Website: http://des.laurentian.ca/people/faculty/richard-s-smith

Title:  Electromagnetic inversion: challenges and approaches to solutions

Outline:  The presentation will discuss some of the challenge of EM inversion: 1) too little data, 2) too many unknowns, 3) no linear solutions, how to select an initial guess, 4) how to discretize the earth and how to select a solution from the many possible solutions.  The presentation will discuss the different approaches that people have been taken to the EM inversion problem and how each approach is designed in some way to deal with some of the issues.
Dima Amine,  Geosoft Inc.

Website:  http://www.geosoft.com/voxi

Title:  A Comparison of Quasi-3D Inversions of Frequency Domain EM Data

Outline:  Full 3D EM inversion requires calculation of the 3D induced current in the earth whereas the Quasi-3D approximations are based on a full 3D inversion but with a simplified, approximate, induced current flow in the earth. We demonstrate two Quasi-3D approximations by comparing their response over the interface of a quarter-space model with the full AEM response, and then demonstrate the methods on a challenging synthetic model and on field data.
Leif Cox,  TechnoImaging LLC

Website:  www.technoimaging.com

Title:  Practical aspects of large-scale inversion

Outline:  Large-scale inversion requires a somewhat different approaches than deposit scale inversion.  Either computation or physics-based compression must be used to enable practical run times.  Data need to be carefully and often adaptively weighted to ensure uniform fit across all inversion regions.  Model weights should be applied to give uniform importance to each model parameter, both to account for sensitivity variations with depth and variations across different parameters such as conductivity and chargeability.  We describe how to make intelligent choices for these and other parameters of inversion. Case studies represent challenges and solutions in large-scale inversions of the airborne EM data.
Colin Farquharson,  Memorial University of Newfoundland

Website:  http://www.esd.mun.ca/~farq/

Title:  Towards Real Earth Models — Computational Geophysics on Unstructured Tetrahedral Meshes?

Outline:  When visualizing and modelling the subsurface in the context of mineral exploration, geologists use 3D Earth models that are made up of tessellated wireframe surfaces. In contrast, we geophysicists have so far used almost exclusively rectilinear meshes to parameterize our Earth models. Wouldn’t it be better if our geophysical models were parameterized in a way that was consistent with – meshed seamlessly with – geological models? An Earth model could then be a single unified, integrated entity that served as both a geological model and a geophysical model. I shall present some examples of the work we’ve been doing to try to achieve this goal and some of the challenges that we face.
Peter Fullagar,  FGCL Consulting Ltd.

Website:  www.fullagargeophysics.com

Title:  Fast 3D inversion of transient electromagnetic (TEM) resistive limit data

Outline:  A fast 3D inversion scheme has been developed for time-integrated (resistive limit) TEM data. The resistive limit inversion is up to 100 times faster than “rigorous” 3D TEM inversion. The software can advance integrated interpretation by performing inversion on a geological model. The inversion scheme is illustrated via application to airborne, ground, and downhole TEM data.
Eldad Haber:  University of British Columbia

Website:  www.math.ubc.ca/~haber

Title:  3D inversion of airborne data

Outline:  In this talk we will show how common airborne data sets can be inverted in 3D in order to give geologically meaningful information,  We use both synthetic and field examples
Michal Kolaj,  Laurentian University
Website:  http://des.laurentian.ca/people/phd-studentsTitle:  Inductive electromagnetic data interpretation using a three-dimensional distribution of three-dimensional magnetic or electric dipolesAuthors:  Michal Kolaj1 and Richard Smith1
1Laurentian University, Department of Earth Sciences, Sudbury, Ontario, Canada

Outline:  We invert inductive magnetic field data, at a given fixed-time or frequency, for the causative subsurface current system which we represent with a 3D distribution of 3D magnetic (closed loop current) or electric (line current) dipoles. The methodology is tested on synthetic plate data and two field examples; a deep massive sulfide (mineral exploration target) and a near-surface mine tailings pond (engineering/environmental study).
Doug Oldenburg:  University of British Columbia

Website:  www.gif.eos.ubc.ca

Title:  Can airborne IP be valuable for kimberlite exploration?

Authors:  Douglas W. Oldenburg1 and Seogi Kang1
1UBC-GIF, Vancouver, British Columbia, Canada

Outline:  Recent developments in airborne TEM inversion to recover 3D IP structures are applied to Tli Kwi Cho (TKC). We present the basic procedure by which  time channels, that have significant IP response,  are first subjected to an EM decoupling procedure and then inverted to recover a 3D pseudo-chargeability at each time. A subsequent inversion carried out for each volumetric cell recovers estimates of Cole-Cole parameters for that cell. For TKC the recovered decay times for the three rock units PK, HK, XVK, are distinctly different. Laboratory analysis of core samples supports this conclusion.
Bill Petrick, Industrial Imaging Co., Inc.

Website:  www.industrialimaging.com

Title:  Pitfalls in 2D AMT Inversion

Outline:  AMT is a powerful tool for minerals and water exploration.  It is common practice to throw a few AMT (or CSAMT) profiles across a project and hope for the best.  I’ll explain the problems with this exploration approach and a much better way to design an AMT survey.
Phil Wannamaker,  University of Utah, Energy & Geoscience Institute

Website:  https://egi.utah.edu/about/staff/phil-wannamaker/

Title:  Three-dimensional magnetotelluric inversion using deformed hexahedral edge finite elements and direct solvers parallelized on SMP computers.

Authors:  Phil Wannamaker1, Michal Kordy1, Virginie Maris2, Elena Cherkaev1, and Graham Hill3
1UofU – EGI, Salt Lake City, UT, USA; 2Universität Trier, Trier, Germany; 3GNS, Lower Hutt, Wellington, New Zealand

Outline:  We describe a new algorithm based upon deformable hexahedral finite elements solving the electric field for 3D inversion of MT responses including substantial topographic variations. Direct solutions are used throughout, including the finite element system matrix, the jacobians and the Gauss-Newton parameter step matrix. The last step is achieved by transforming to data-space. Field examples utilizing of order one million parameters will be presented, run on single-box, large-RAM, multi-core workstations.