Transforming geology into seismic

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Hart (2013). ©SEG/AAPGForward modeling of seismic data is the most important workflow that nobody does.

Why is it important?

  • Communicate with your team. You know your seismic has a peak frequency of 22 Hz and your target is 15–50 m thick. Modeling can help illustrate the likely resolution limits of your data, and how much better it would be with twice the bandwidth, or half the noise.
  • Calibrate your attributes. Sure, the wells are wet, but what if they had gas in that thick sand? You can predict the effects of changing the lithology, or thickness, or porosity, or anything else, on your seismic data.
  • Calibrate your intuition. Only by predicting the seismic reponse of the geology you think you're dealing with, and comparing this with the response you actually get, can you start to get a feel for what you're really interpreting. Viz Bruce Hart's great review paper we mentioned last year (right).

Why does nobody do it?

Well, not 'nobody'. Most interpreters make 1D forward models — synthetic seismograms — as part of the well tie workflow. Model gathers are common in AVO analysis. But it's very unusual to see other 2D models, and I'm not sure I've ever seen a 3D model outside of an academic environment. Why is this, when there's so much to be gained? I don't know, but I think it has something to do with software.

  • Subsurface software is niche. So vendors are looking at a small group of users for almost any workflow, let alone one that nobody does. So the market isn't very competitive.
  • Modeling workflows aren't rocket surgery, but they are a bit tricky. There's geology, there's signal processing, there's big equations, there's rock physics. Not to mention data wrangling. Who's up for that?
  • Big companies tend to buy one or two licenses of niche software, because it tends to be expensive and there are software committees and gatekeepers to negotiate with. So no-one who needs it has access to it. So you give up and go back to drawing wedges and wavelets in PowerPoint.

Okay, I get it, how is this helping?

We've been busy lately building something we hope will help. We're really, really excited about it. It's on the web, so it runs on any device. It doesn't cost thousands of dollars. And it makes forward models...

That's all I'm saying for now. To be the first to hear when it's out, sign up for news here:

This will add you to the email list for the modeling tool. We never share user details with anyone. You can unsubscribe any time.

Seismic models: Hart, BS (2013). Whither seismic stratigraphy? Interpretation, volume 1 (1). The image is copyright of SEG and AAPG.

Creating in the classroom

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The day before the Atlantic Geoscience Colloquium, I hosted a one-day workshop on geoscience computing to 26 maritime geoscientists. This was my third time running this course. Each time it has needed tailoring and new exercises to suit the crowd; a room full of signal-processing seismologists has a different set of familiarities than one packed with hydrologists, petrologists, and cartographers. 

Easier to consume than create

At the start of the day, I asked people to write down the top five things they spend time doing with computers. I wanted a record of the tools people use, but also to take collective stock of our creative, as opposed to consumptive, work patterns. Here's the result (right).

My assertion was that even technical people spend most of their time in relatively passive acts of consumption — browsing, emailing, and so on. Creative acts like writing, drawing, or using software were in the minority, and only a small sliver of time is spent programming. Instead of filing into a darkened room and listening to PowerPoint slides, or copying lectures notes from a chalkboard, this course was going to be different. Participation mandatory.

My goal is not to turn every geoscientist into a software developer, but to better our capacity to communicate with computers. Giving people resources and training to master this medium that warrants a new kind of creative expression. Through coaching, tutorials, and exercises, we can support and encourage each other in more powerful ways of thinking. Moreover, we can accelerate learning, and demystify computer programming by deliberately designing exercises that are familiar and relevant to geoscientists. 

Scientific computing

In the first few hours students learned about syntax, built-in functions, how and why to define and call functions, as well as how to tap into external code libraries and documentation. Scientific computing is not necessarily about algorithm theory, passing unit tests, or designing better user experiences. Scientists are above all interested in data, and data processes, helped along by rich graphical displays for story telling.

Elevation model (left), and slope magnitude (right), Cape Breton, Nova Scotia. Click to enlarge.

In the final exercise of the afternoon, students produced a topography map of Nova Scotia (above left) from a georeferenced tiff. Sure, it's the kind of thing that can be done with a GIS, and that is precisely the point. We also computed some statistical properties to answer questions like, "what is the average elevation of the province?", or "what is the steepest part of the province?". Students learned about doing calculus on surfaces as well as plotting their results. 

Programming is a learnable skill through deliberate practice. What's more, if there is one thing you can teach yourself on the internet, it is computer programming. Perhaps what is scarce though, is finding the time to commit to a training regimen. It's rare that any busy student or working professional can set aside a chunk of 8 hours to engage in some deliberate coaching and practice. A huge bonus is to do it alongside a cohort of like-minded individuals willing and motivated to endure the same graft. This is why we're so excited to offer this experience — the time, help, and support to get on with it.

How can I take the course?

We've scheduled two more episodes for the spring, conveniently aligned with the 2014 AAPG convention in Houston, and the 2014 CSPG / CSEG convention in Calgary. It would be great to see you there!

Eventbrite - Agile Geocomputing  Eventbrite - Agile Geocomputing

Or maybe a customized in-house course would suit your needs better? We'd love to help. Get in touch.

A long weekend of Atlantic geology

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The Atlantic Geoscience Society Colloquium was hosted by Acadia University in Wolfville, Nova Scotia, this past weekend. It was the 50th Anniversay meeting, and attracted a crowd of about 175 geoscientists. A few members were able to reflect and tell stories first-hand of the first meeting in 1964.

It depends which way you slice it

Nova Scotia is one of the best places for John Waldron to study deformed sedimentary rocks of continental margins and orogenic belts. Being the anniversary, John traced the timeline of tectonic hypotheses over the last 50 years. From his kinematic measurements of Nova Scotia rocks, John showed the complexity of transtensional tectonics. It is easy to be fooled: you will see contraction features in one direction, and extension structures in another direction. It all depends which way you slice it. John is a leader in visualizing geometric complexity; just look at this animation of piecing together a coal mine in Stellarton. Oh, and he has a cut and fold exercise so that you can make your own Grand Canyon! 

The application of the Law of the Sea

In September 2012 the Bedford Institute of Oceanography acquired some multibeam bathymetric data and applied geomorphology equations to extend Canada's boundaries in the Atlantic Ocean. Calvin Campbell described the cruise as like puttering from Halifax to Victoria and back at 20 km per hour, sending a chirp out once a minute, each time waiting for it to go out 20 kilometres and come back.

The United Nation's Convention on the Law of the Sea (UNCLOS) was established to define the rights and responsibilities of nations in their use of the world's oceans, establishing guidelines for businesses, the environment, and the management of marine natural resources. A country is automatically entitled to any natural resources found within a 200 nautical mile limit of its coastlines, but can claim a little bit more if they can prove they have sedimentary basins beyond that. 

Practicing the tools of the trade

Taylor Campbell, applied a post-stack seismic inversion workflow to the Penobscot 3D survey and wells. Compared to other software talks I have seen in industry, Taylor's was a quality piece of integrated technical work. This is even more commendable considering she is an undergraduate student at Dalhousie. My only criticism, which I shared with her after the talk was over, was that the work lacked a probing question. It would have served as an anchor for the work, and I think is one of the critical distinctions between scientific pursuits and engineering.

Image courtesy of Justin Drummond, 2014, personal communication, from his expanded abstract presented at GSA 2013.

Practicing rational inquiry

Justin Drummond's work, on the other hand, started with a nugget of curiosity: How did the biogeochemical cycling of phosphorite change during the Neoproterozoic? Justin's anchoring question came first, only then could he think about the methods, technologies and tools he needed to employ, applying sedimentology, sequence stratigraphy, and petrology to investigate phosphorite accumulation in the Sete Lagoas Formation. He won the award for Best Graduate Student presentation at the conference.

It is hard to know if he won because his work was so good, or if it was because of his impressive vocabulary. He put me in mind of what Rex Murphy would sound like if he were a geologist.

The UNCLOS illustration is licensed CC-BY-SA, by Wikipedia users historicair and MJSmit.

Atlantic geology hits Wikipedia

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WikiProject Geology is one of the gathering places for geoscientists in Wikipedia.Regular readers of this blog know that we're committed to open scientific communication, and that we're champions of wikis as one of the venues for that communication, and that we want to see more funky stuff happen at conferences. In this spirit, we hosted a Wikipedia editing session at the Atlantic Geoscience Society Colloquium in Wolfville, Nova Scotia, this past weekend. 

As typically happens with these funky sessions, it wasn't bursting at the seams: The Island of Misfit Toys is not overcrowded. There were only 7 of us: three Agilistas, another consultant, a professor, a government geologist, and a student. But it's not the numbers that matter (I hope), it's the spirit of the thing. We were a keen bunch and we got quite a bit done. Here are the articles we started or built upon:

The birth of the Atlantic Geoscience Society page gave the group an interesting insight into Wikipedia's quality control machine. Within 10 minutes of publishing it, the article was tagged for speedy deletion by an administrator. This sort of thing is always a bit off-putting to noobs, because Wikipedia editors can be a bit, er, brash, or at least impersonal. This is not that surprising when you consider that new pages are created at a rate of about one a minute some days. Just now I resurrected a stripped-down version of the article, and it has already been reviewed. Moral: don't let anyone tell you that Wikipedia is a free-for-all.

All of these pages are still (and always will be) works in progress. But we added 5 new pages and a substantial amount of material with our 28 or so hours of labour. Considering most of those who came had never edited a wiki before, I'm happy to call this a resounding success. 

Much of my notes from the event could be adapted to any geoscience wiki editing session — use them as a springboard to get some champions of open-access science together at your next gathering. If you'd like our help, get in touch.

Rock Hack 2014

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We're hosting another hackathon! This time, we're inviting geologists in all their colourful guises to come and help dream up cool tools, find new datasets, and build useful stuff. Mark your calendar: 5 & 6 April, right before AAPG.

On 4 April there's the added fun of a Creative geocomputing course. So you can learn some skills, then put them into practice right away. More on the course next week.

What's a hackathon?

It's not as scary — or as illegal — as it sounds! And it's not just for coders. It's just a roomful of creative geologists and friendly programmers figuring out two things together:

  1. What tools would help us in our work?
  2. How can we build those tools?

So for example, we might think about problems like these:

  • A sequence stratigraphy calibration app to tie events to absolute geologic time
  • Wireline log 'attributes'
  • Automatic well-to-well correlation
  • Facies recognition from core
  • Automatic photomicrograph interpretation: grain size, porosity, sorting, and so on
  • A mobile app for finding and capturing data about outcrops
  • Sedimentation rate analysis, accounting for unconformities, compaction, and grain size

I bet you can think of something you'd like to build — add it to the list!

Still not sure? Check out what we did at the Geophysics Hackathon last autumn...

How do I sign up?

You can sign up for the creative geocomputing course at Eventbrite.

If you think Rock Hack sounds like a fun way to spend a weekend, please drop us a line or sign up at Hacker League. If you're not sure, please come anyway! We love visitors.

If you think you know someone who'd be up for it, let them know with the sharing buttons below.

The poster image is from an original work by Flickr user selkovjr.