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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

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...

February 10, 2016

Cameco's new uranium discovery revealed

Canada's top uranium producer has a significant new discovery nearby to one of its largest existing mines...

February 9, 2016

NexGen Drills Most Intense Mineralization to Date at Arrow

NexGen announces further results from its on-going six rig 30,000 m winter 2016 drill program on its 100% owned Rook I Property in the Athabasca Basin, Saskatchewan...

February 9, 2016

Rio Tinto scales up its big data ambitions

Rio Tinto is opening its "vast troves" of exploration data to junior explorers in the hopes they will help sift for opportunities and supply ideas and labour...

February 8, 2016

Online portal improves access to geoscience data from Africa

The Botswana Geoscience Institute is launching a Geoscience Portal...

February 8, 2016

5 Best Minerals & Fossils To Buy With Your IRS Tax Refund

You just got your IRS tax refund and now you're presented with some cash to go out and buy one of a kind minerals and fossils from your local...

February 5, 2016

World's largest offshore windfarm to be built off Yorkshire coast

Dong Energy makes final investment decision on 1.2-gigawatt project that will power more than a million UK homes...

February 2, 2016

World's top 10 rookie gold mines

These high-grade mines will soon start competing with gold mining's industry leaders ...

January 25, 2016

Exxon Mobil Corp's defiant outlook predicts Canadian and Venezuelan oilsands output will 'quadruple' over next 24 years

In sharp contrast to the grim medium-term prognosis for the Canadian oilsands, Exxon Mobil Corp. is predicting sunnier times for bitumen in the decades ahead...

January 23, 2016

Magnetic Survey Keeps Cost Down

At a contaminated furniture factory site in North Carolina, a reconnaissance magnetic survey was conducted toward the end of a Phase 2 investigation ...

New Approach to Basement Studies for Oil and Gas Explorers

Often not given its due in oil and gas geophysics, knowledge of basement geology can be critical to exploiting reservoirs including the unconventional.

by Graham Chandler on January 24, 2013 applied

[Click to enlarge]

Magnetic shadowgram illuminated from the north with 70º ‘sun’ inclination. The straight white lines are interpreted lineaments.

[Click to enlarge]

Map of gravity and magnetic anomaly domains of southern and central Alberta Basin, superimposed on a total-field magnetic map. RDH – Red Deer Magnetic High; EH – Eyehill Magnetic High.

Henry Lyatsky has a message for those who explore for oil and gas. As a practicing geophysicist and geologist, this Calgary researcher and consultant is intimately familiar with both professions and has observed the two often don’t converge enough—especially when it comes to basement geology.

“If you want to understand your basin, begin with the basement,” he says. While most geologists in the oil and gas industry recognize this, geophysicists can overlook it in their fixation on the all-important seismic.

Lyatsky sets the picture: “When you are dealing with oil and gas you are dealing with sedimentary rocks which are stratified, kind of flat-lying,” he says. They have relatively uncomplicated structures where seismic methods are ideal. “But when the rocks are all skewed and confused you don’t know what you are getting.” He explains that the sedimentary basin is a geological body; a body of rocks sitting on top of another body of rocks that is commonly a crystalline basement. “It’s like putting a bunch of stuff on top of a table,” he says. “It’s affected by what the table is. If the table is not very steady or is shifting it’s going to shift what’s higher up. So you have to think about the crystalline basement which is not sedimentary but highly metamorphosed; often igneous.”

These are the rocks that mining explorers are accustomed to, says Lyatsky; they are faced with a different rock mass requiring different geophysics. “The rocks are more diverse than you find in oil and gas exploration,” he says. So they rely on a wider range of geophysical techniques that includes magnetic, gravity, electrical, electromagnetic and radiometric.

However, seismic remains critical, indeed indispensable, to oil and gas explorers. But to fully interpret it, geophysicists should have a good knowledge of basement faults and fractures, which have a way of propagating up the sedimentary section. “They affect your depositional patterns, your erosional patterns, your compaction and alteration patterns, your facies distribution, your secondary porosity, your salt dissolution,” advises Lyatsky. “All of these are affected and sometimes controlled by those fractures coming from the basement.”

And basement rocks are not exposed although they can often be seen around the fringe of a sedimentary basin. “But you don’t actually know it,” says Lyatsky. “You don’t see it so you have to be very cautious in making your interpretations—you don’t want to go around inventing things. You have to be very conservative but you have to squeeze every drop of blood out of the stone. And what matters more than anything else are those faults and fractures that are in the basement.”

To know these, you pretty much have to look at gravity and magnetics, says Lyatsky, especially in a mature basin like the Alberta. But not only in mature basins: “If it’s a frontier basin it depends on the basin; if there is a lot of structure or vertical displacements and faults, I still use a mix of gravity and magnetics.”

Gravity and magnetic data are available free of charge from Canada’s federal government. “The cost is zero. And if the basement is deep enough, in most of the Alberta basin for example, government data are sufficient for probably 80% of the basin to resolve all of your basement anomalies,” says Lyatsky. Around the edges of the basin, for example in northeastern Alberta, it may not be sufficient so flying tighter surveys may be in order. “But before you do that and commit capital, spend a fraction of that cost and go over the government data, then you can make your decisions,” he says. “Chances are you will save a ton of money.”

To assist explorers in doing this, Lyatsky has collaborated with the Alberta Geological Survey to publish a gravity and magnetic atlas of basement structure in central and southern Alberta, all from publicly available data (AGS Special Report 072). “I saw a need for it,” he says. “Gravity and magnetic work has been done in this basin since 1947—the original publications were coming out in the 50s. People thought Leduc must be sitting on a basement fault of some kind. That particular fault is found more by gravity than magnetics.” But as time went on it became too academic, he says. So as someone who could straddle the academic and commercial geophysics, he pulled it together in a more readily useable format.

To use it with seismic data, he has some suggestions for oil and gas geophysicists. “When it comes to integration of the data, you’ve got to start thinking like a geologist,” he advises. “Stop thinking like a physicist because the purpose is to get geological information—so at some point you have to switch to the geology mode.” Trained in both, he usually helps his clients with that as a project progresses. “Geologists come in and say, what am I supposed to do with this? You begin to tell them in their own language—to avoid the disconnect—saying this is what it can do for you.”

For geophysicists, Lyatsky points out that in platformal basins like the Alberta or the Williston, a lot of the basement fractures and faults have too little vertical offset to be visible in seismic displays at all. “Lineament maps compared with the known geology of play intervals in the sedimentary section might suggest basement control if something linear in the play interval lines up with basement-sourced lineaments,” he says. For example, if a linear string of oil or gas reservoirs coincides with a gravity or magnetic basement lineament and this lineament continues beyond the reservoir string, it might be worth asking if there is fault control on the reservoirs and if more reservoirs might exist along the continuation of the basement lineament.

To integrate the gravity and magnetics with seismic data, “the best piece of integration software is the human brain,” says Lyatsky. But he also uses Geosoft routinely. “I used it to make the atlas, and I use it commercially. If you are working to make maps for extracting subtle anomalies, from what I have seen there is nothing better. You have a lot of processing options and they are very good.”

A good picture of the basement is important when it comes to the newer technologies, particularly horizontal multistage fracking—where a liquid, usually water, is blended with a proppant and other substances and injected at high pressure to fracture tight formations like shale and release oil or gas. “We are spending billions of dollars on fracking and that is how you produce [these formations],” says Lyatsky. But with a more intimate knowledge of the basement structure, parts of it may already be fracked. “If you are fracking you want to know what fractures already exist. You want to understand where Mother Nature put her own fractures before you start coming in and spending money to make your own—a lot of that is controlled from the basement up. So every kind of level you look, the more you know about the basement, the easier it is to explore the basin.”

He says it’s good for all formations: primary porosity, secondary porosity, conventional, unconventional, tight. “You are pumping your fluids in, you want to know where they’re going to go. Secondly if it’s already fractured maybe your strategy should be different.” Basement knowledge goes for oil sands applications, too; another unconventional resource, especially with respect to in situ techniques. “With in situ [such as SAGD, or steam-assisted gravity drainage] you don’t dig, you drill and loosen up the bitumen with steam to produce it from a well. You want to know where your faults and fractures are. You are putting fluids into your formation, will they go where you want?”

So how should the industry steer oil and gas geophysicists to the basement, so to speak? Lyatsky reckons you need to start at the beginning of their education. “You go to people who train students and you tell them ‘you guys are doing a, b and c; what we think you should be doing is x, y and z as well as a, b and c’,” he says. “When academics talk to industry, I think it’s the opportunity to tell them what they need to hear. The second thing is, you do it on the demand side; you go to the students themselves.” He never misses a chance to talk to students, and advocates telling them that what they’re getting is constraining their careers and doing them a disservice in the long run.

It has been said that everyone should learn to recognize their faults. Adding to that, Lyatsky has another message for oil and gas geophysicists: “You cannot get away from having to understand your basement faults.”