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Thursday
Nov082012

Brittleness and robovibes

Day 3 of the SEG Annual Meeting was just as rammed with geophysics as the previous two days. I missed this morning's technical program, however, as I've taken on the chairpersonship (if that's a word) of the SEG Online Committee. So I had fun today getting to grips with that business. Aside: if you have opinion's about SEG's online presence, please feel free to send them my way.

Here are my highlights from the rest of the day — both were footnotes in their respective talks:

Brittleness — Lev Vernick, Marathon

Evan and I have had a What is brittleness? post in our Drafts folder for almost two years. We're skeptical of the prevailing view that a shale's brittleness is (a) a tangible rock property and (b) a function of Young's modulus and Poisson's ratio, as proposed by Rickman et al. 2008, SPE 115258. To hear such an intellect as Lev declare the same today convinced me that we need to finish that post — stay tuned for that. Bottom line: computing shale brittleness from elastic properties is not physically meaningful. We need to find more appropriate measures of frackability, which Lev pointed out is, generally speaking, inversely proportional to organic content. This poses a basic conflict for those exploiting shale plays. 

Robovibes — Guus Berkhout, TU Delft

At least 75% of Berkhout's talk went by me today, mostly over my head. I stopped writing notes, which I only do when I'm defeated. But once he'd got his blended source stuff out of the way, he went rogue and asked the following questions:

  1. Why do we combine all seismic frequencies into the device? Audio got over this years ago (right).
  2. Why do we put all the frequencies at the same location? Viz 7.1 surround sound.
  3. Why don't we try more crazy things in acquisition?

I've wondered the same thing myself — thinking more about the receiver side than the sources — after hearing about the brilliant sampling strategy the Square Kilometer Array is using at a PIMS Lunchbox Lecture once. But Berkhout didn't stop at just spreading a few low-frequency vibrators around the place. No, he wants robots. He wants an autonomous army of flying and/or floating narrow-band sources, each on its own grid, each with its own ghost matching, each with its own deblending code. This might be the cheapest million-channel acquisition system possible. Berkhout's aeronautical vibrator project starts in January. Seriously.

More posts from SEG 2012. 

Speaker image is licensed CC-BY-SA by Tobias Rütten, Wikipedia user Metoc.

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Reader Comments (3)

Hi Matt
You're keeping busy!
A quick comment on question 1: Chris Liner commented during his 2012 Calgary DISC that one day broadband seismic will be out of fashion. He has some good examples of what can be done with narrow band data in chapter 6 of the book.
Looking forward to your brittleness post.

November 8, 2012 | Unregistered Commentermatteo

@Matteo: OK, you made me buy his course notes :)

November 8, 2012 | Registered CommenterMatt Hall

Matt:
Yes, please do post your 'What is Brittleness?' blog. It was evident from the number of papers referring to Rickman's paper and definition, and the number of negative comments about this definition, that this is rapidly becoming a major topic in unconventional shale geophysics.

November 17, 2012 | Unregistered CommenterScott Singleton

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