The people, science and technology behind discovery

Subscribe to the Magazine

Get new articles sent directly to
your mailbox.

Join the network

Twitter Updates Group Forum

Earth Explorer is an online source of news, expertise and applied knowledge for resource explorers and earth scientists. Sponsored by Geosoft.

News & Views

News Archive

December 7, 2016

Geosoft introduces IP and resistivity inversion in VOXI Earth Modelling

Geosoft has added induced polarization and resistivity data inversion to its VOXI Earth Modelling 3D inversion software service. Geoscientists are now able to create detailed 3D models of conductivity and chargeability from IP and resistivity survey data with VOXI. The resulting models can assist in interpreting and targeting regions for mineral and environmental applications...

December 5, 2016

Mexico's Deepwater Round Exceeds Expectations

Some of the world's biggest oil companies showed up Dec. 5 and agreed to invest on the Mexican side of the Gulf of Mexico, proving that deepwater exploration still has a pulse despite challenging market conditions...

November 30, 2016

Magnetic inversion results for Ngamiland available for download

A regional-scale geophysical inversion of magnetic field data in the Ngamiland region of northwestern Botswana is now available for download from the Botswana Geoscience Portal, a partnership initiative of the Botswana Geoscience Institute, industry sponsors and Geosoft...

November 30, 2016

LIGO Resumes Search for Gravitational Waves

After a series of upgrades, the twin detectors of LIGO, the Laser Interferometer Gravitational-wave Observatory, have turned back on and resumed their search for ripples in the fabric of space and time known as gravitational waves. LIGO transitioned from their engineering test runs to full science observations at 8 a.m. Pacific Standard Time on November 30...

November 9, 2016

International Volcano Scientists Unite

For the first time, the United States will host the international Volcano Observatory Best Practices workshop, previously held only in Italy. The workshop will take place this month in Vancouver, Washington. It is designed specifically for volcano observatories around the world and their staff to exchange ideas and best practices with each other...

October 4, 2016

USGS Assesses Mineral Potential for Sagebrush Habitats in Six Western States

USGS has completed a comprehensive assessment and inventory of potential mineral resources covering approximately 10 million acres of Federal and adjacent lands in Idaho, Montana, Nevada, Oregon, Utah and Wyoming...

October 3, 2016

Uganda Targets Up to U.S.$100 Million for Mineral Exploration

Uganda is well endowed with mineral resources and, like many naturally-gifted African countries, is becoming keen on ensuring that these resources play a transformative role in its long-term structural transformation dream - the Vision 2040...

September 9, 2016

Small-Scale Fishers Get A Big Boost With First-Of-Its Kind Impact Investment Fund

Conservation organization Rare announces the Meloy Fund for Small-Scale Fisheries at Our Ocean Conference. The Global Environment Facility, one of the largest funders of conservation worldwide, will be investing $6 million into the fund...

September 1, 2016

Scientists take to the skies to track West African pollution

Scientists operating research aircraft over West Africa have detected organic materials in the atmosphere over a number of urban areas, contributing to concerns of the rise in pollution across the region...

August 17, 2016

New IGS Xplore prospectivity maps for Botswana

International Geoscience Services have released a series of base metal prospectivity maps for the Ngamiland District of northwestern Botswana using free geodata available on the recently-launched Botswana Geoscience Portal, hosted by Geosoft. The maps identify favorable areas for copper, zinc and lead mineralization using geological, geochemical and geophysical datasets downloaded directly from the portal.

August 11, 2016

NexGen Makes New High Grade Discovery

NexGen Energy reported the discovery of a new high grade zone of mineralization 4.7 km northeast of the Arrow Deposit as part of an on-going summer drilling program on its 100% owned, Rook I property, Athabasca Basin, Saskatchewan...

August 10, 2016

Rampion UXO Disposal to Take Place This Week

E.ON has confirmed that the two unexploded devices, detected along the Rampion offshore cable route will be safely disposed this week following the consultation with the Marine Management Organisation...

August 9, 2016

Diamonds In The Rough: E&Ps Find New Reserves In Mature Basins

The oil industry’s history demonstrates clearly that new plays and prospects have long been found in mature basins that were thought to be well on the way to being squeezed dry. Through the acquisition of new data, developing new concepts and coming up with fresh interpretations, long-producing basins around the world from the North Sea to Malaysia have continued to reveal new riches...

August 8, 2016

Northern Shield Identifies High Quality VTEM Targets at Séquoi

Northern Shield Resources announced the results of the interpretation and modelling of the VTEM survey from the Séquoi Property in the Labrador Trough of Quebec . Séquoi is owned 100% by Northern Shield and is being explored for Noril'sk style Ni-Cu-PGE massive sulphides. After geophysical modelling and interpretation of the VTEM data from Séquoi, six VTEM anomalies of significant interest have been identified...

August 3, 2016

Rio Tinto tailors big data drive to copper

Rio Tinto will put the weight of an exploration big data push and its newly-formed Growth and Innovation group behind its desire to identify a "tier 1" copper asset. Speaking at the annual Diggers & Dealers conference in Kalgoorlie, Growth and Innovation group executive Stephen McIntosh said Australia was "overdue for a tier 1" mineral discovery of any type...

August 1, 2016

Tetra Tech Awarded $200 Million Navy CLEAN Contract

Tetra Tech announced that it has been awarded a $200 million, single-award contract by Naval Facilities Engineering Command (NAVFAC) Atlantic. Through the Comprehensive Long-term Environmental Action Navy (CLEAN) contract, Tetra Tech will provide environmental engineering support services to installations within the NAVFAC Atlantic Area of Responsibility...

May 3, 2016

NATO Science for Peace and Security (SPS), MODUM Partners announce "Young Scientist Summer School on Sea Dumped Chemical Weapons"

This international project cooperates closely with CHEMSEA (Search and Assessment of Chemical Weapons) Project for and sharing and knowledge transfer...

April 12, 2016

Monday mad rush for gold stocks

Renewed optimism about the outlook for gold saw investors pile back into gold stocks, pushing many stock to 52-week highs in heavy volumes...

April 11, 2016

Medgold Resources: Continues to Expand the Boticas Gold Project, Portugal; Proposes $200,000 Private Placement

Medgold Resources is pleased to announce new assay results from contiguous rock-chip sampling from the Limarinho South zone at its Boticas gold project in Portugal, which include a highlight of 6.0m @ 5.7 g/t Au...

April 8, 2016

De-carbonizing our energy sector

Nuclear energy currently provides around 11 percent of the world's electricity. China, the European Union, the United States, India, Russia, South Korea, and other nations’ have major existing fleets...

April 1, 2016

Follow-Up Drilling Results Indicate Wide Gold Zones at Hendricks Gold Discovery

Gascoyne Resources Limited announced that it has received the final assay results from the 10,000 metre aircore exploration drilling programme...

March 26, 2016

The Oil Market Is Finally Hitting Its Breaking Point

After a significant reduction in investments over the past two years, oil companies can no longer overcome the production declines from legacy wells...

March 15, 2016

N-Sea Expands into the French Offshore Wind Industry

Subsea IMR provider, N-Sea, has signed a letter of intent with CERES Recherches & Expertise Sous-Marine and TechSub Industrie Environement, to provide subsea survey, installation and remediation services to the French offshore wind industry...

March 9, 2016

PDAC 2016 Convention Exceeds 22,000 Attendees

Optimism and opportunity abounded at the PDAC 2016 Convention of The Prospectors & Developers Association of Canada in spite of recent industry challenges...

March 3, 2016

6 Alpha Launches EOD Contracting Division

6 Alpha Associates, a specialist risk consultancy practice, with expertise in the assessment and management of unexploded ordnance, has launched a dedicated explosive ordnance disposal division...

Modelling the Earth through Inversion

Interview with Geosoft Chief Technologist Ian MacLeod on the benefits of 3D inversion modelling and the company’s plans to introduce voxel inversion modelling technology as an online service in 2011.

November 5, 2010

How would you describe the principle of 3D inversion as it applies to geophysical exploration?

When we conduct geophysical surveys we seek information about the underlying and hidden geology that gives rise to the values we observe on the Earth’s surface. For example, the observed gravity field varies as a function of the underlying rock density, and a magnetic survey varies as a function of rock susceptibility. But the 3D relationship is very complex. What we see at the surface depends on the depth and shape of various features, and there are many distributions of density or susceptibility or other rock properties that can explain what we observe.

The process of 3D inversion seeks to produce the most likely distribution of physical rock parameters that explain what we have observed. As the process is non-unique, the ability of the inversion process to produce reasonable results, combined with reasonable constraints, and the experience of the interpreter is important.

How much new information about the Earth’s geology can be gleaned using inversion?

Perhaps the most important advance is our ability to visualize and describe the Earth as it is – a 3D volume of complex geology. The process of 3D inversion describes the earth as a collection of small rectangular cells (typically 5 to 50 metres in size), each with a different physical parameter (density, susceptibility, magnetic vector, etc.). We call this a voxel model of the earth. This is becoming a common model that can be used in a variety of visualization systems and combined with other geological information and interpretive processes. The ability to share these types of 3D geophysical models with other exploration disciplines is key to modern exploration success.

Geophysical interpretation has always been about understanding the subsurface geology. This is not new. What makes Geosoft’s approach different?

Historically, the skills and visualization abilities of the interpreter together with manageable 2-D and simpler 3D tools have been used to target features of interest and help resolve geologic uncertainties. However, the available tools have been limited or very difficult to use. While 3D inversion using voxel earth models has been around for well over 10 years, it has only been accessible to highly-trained specialists with powerful computer technology.

At Geosoft, we’ve focused on making complex techniques simpler and more accessible to all geoscientists. Our latest developments in inversion modelling combine a well-integrated workflow and simplified interpreter interface with network technology that harnesses internet-based servers to perform computer-intensive inversions. The workflow will allow interpreters to efficiently get information into the inversion process, apply constraints and evaluate results. They will be able to easily export and share results with team members. The delivery of inversion capabilities as an online service will give interpreters access to the most advanced 3D inversion modelling capabilities available today, without consuming desktop processing power.

What types of constraints enhance the effectiveness of geophysical inversion modelling?

While the earth can be infinitely complex, when we conduct exploration we generally have pretty good models of what we are looking for and the environments in which we are working. For example, in petroleum exploration we seek petroleum traps in sedimentary geology, and in hard-rock mineral exploration we understand the basic geologic plays – things such as strike and dip of rocks, and the style of complexity for the target deposits, and so on. We also have other information to help guide us – seismic interpretations in petroleum, or surface mapping, depth of overburden and possibly drilling information in mineral exploration plays. All this information allows us to build constraints that help improve the accuracy of 3D inversions.

However, the workflow to define and introduce constraints continues to be a challenge. With Geosoft voxel inversion technologies, we have taken a big step in making this as simple as possible, and in on-going development over the coming months and years we will continue to improve in this area.

How would you describe inversion’s cost and time benefits?

Understanding the time and cost benefit depends on the perspective you’re taking, whether petroleum exploration or mineral exploration.

Petroleum exploration today is really about deep drilling in frontier areas of the world. In these environments the costs of drilling exploration wells can be extremely expensive – 10’s to 100’s of millions of dollars. With such a significant investment at stake, explorers need to apply every possible piece of information to give exploration wells the best chance of success. Of course, 3D seismic surveys continue to be the primary source of information, but increasingly gravity and magnetic interpretations are being used to resolve doubts or verify seismic interpretations. In the end, the best interpretation of the earth explains everything, including the gravity and magnetic field. In petroleum exploration, 3D modelling and inversion around a voxel model of the earth is particularly powerful as this is the way petroleum explorers have become accustomed to thinking about the subsurface. Removing the barriers to integrating gravity and magnetic inversion with seismic interpretation environments is adding to the over-all confidence of exploration decisions, and hence the cost/benefit is well justified.

In mineral exploration, particularly greenfield exploration, one of the important drivers of success is the ability to make good decisions, test the potential of a property through drilling, and move on to the next property. Success over time (among other things) is proportional to the number of targets tested. In many cases, these time limitations have prevented the use of complex 3D inversion interpretations, because producing inversions currently takes a lot of time, and there are a limited number of experts available to do them. As a result 3D inversion has been rarely used. We believe that making 3D inversion fast and accessible to more explorers will change the cost/benefit scenario significantly, and this will lead to more exploration success through targeting decisions that benefit from an improved three dimensional understanding of the subsurface.

What specialized skills and knowledge are required to use the inversion modelling technique?

While our goal is to make access to the technology as simple as possible, geophysical inversion still requires both practical experience and a good understanding of both geology and physics. Having removed the accessibility barriers we will be supporting the education of interpreters through good help systems, on-line training and the development of community knowledge that can be shared among interpreters. Here again is where we see now-common internet technology and collaboration helping a great deal. We want to make it easy and natural for professional explorers to collaborate and share knowledge, skills and information.

How can inversion be incorporated into the early stages of planning an exploration program? How can it be applied to programs already under way?

Once an exploration team has a good idea of the type of target they seek, what we call “forward modelling” of the target is an important step to determine the value of conducting various geophysical surveys. While this is not inversion, this is a capability that comes from the types of systems we are building. An exploration team can create a model of the 3D earth, that they expect to find, and from that predict what a survey would measure. This gives the team the confidence that a particular method is appropriate for what they seek.

As for exploration programs already under way, geophysical surveys – particularly magnetic and gravity surveys - are today already standard methods that provide both direct targeting information and are useful as an aid to general geologic interpretation.  Because this data already exists it is often useful to use 3D inversion of select parts of existing prospects to add to the existing knowledge.  So we have the data – what is it telling us in 3D?