Where is the ground?

This is the upper portion of a land seismic profile in Alaska. Can you pick a horizon where the ground surface is? Have a go at pickthis.io.

Pick the Ground surface at the top of the seismic section at pickthis.io.

Picking the ground surface on land-based seismic data is not straightforward. Picking the seafloor reflection on marine data, on the other hand, is usually a piece of cake, a warm-up pick. You can often auto-track the whole thing with a few seeds.

Seafloor reflection on Penobscot 3D survey, offshore Nova Scotia. from Matt's tutorial in the April 2016 The Leading Edge, The function of interpolation.

Why aren't interpreters more nervous that we don't know exactly where the surface of the earth is? I'm sure I'm not the only one that would like to have this information while interpreting. Wouldn't it be great if land seismic were more like marine?

Treacherously Jagged TopographY or Near-Surface processing ArtifactS?

If you're new to land-based seismic data, you might notice that there isn't a nice pickable event across the top of the section like we find in marine seismic data. Shot noise at the surface has been muted (deleted) in processing, and the low fold produces an unclean, jagged look at the top of the section. Additionally, the top of the section, time-zero — the seismic reference datum — usually floats somewhere above the land surface — and we can't know where that is unless it can be found in the file header, or looked up in the processing report.

The seismic reference datum, at a two-way time of zero seconds on seismic data, is typically set at mean sea level for offshore data. For land data, it is usually chosen to 'float' above the land surface.

Reframing the question

This challenge is a bit of a trick question. It begs the viewer to recognize that the seemingly simple task of mapping the ground level on a land seismic section is actually a rudimentary velocity modeling or depth conversion exercise in itself. Wouldn't it be nice to have the ground surface expressed as pickable seismic event? Shouldn't we have it always in our images? Baked into our data, so to speak, such that we've always got an unambiguous pick? In the next post, I'll illustrate what I mean and show what's involved in putting it in. 

In the meantime, I challenge you to pick where you think the (currently absent) ground surface is on this profile, so in the next post we can see how well you did.

Pick This again, again

Today we're proud to be launching the latest, all new iteration of Pick This!

Last June I told you about some new features we'd added to our social image interpretation tool. This new release is not really about features, but more about architecture. Late in 2015, we were challenged by BG Group, a UK energy company, to port the app to Amazon's cloud (AWS), so that they could run it in their own environment. Once we'd done that, we brought the data over from Google — where it was hosted — and set up the new public site on AWS. It will be much easier for us to add new features to this version.

One notable feature is that you no longer have to have a Google account to log in! This may have been a show-stopper for some people.

The app has been completely re-written from scratch, so there are a few differences. But fundamentally it's the same as before — you can ask your peers questions about images, and they can draw their answers. For example, Don Herron's "Where's the unconformity?" now has over 450 interpretations!

As we improve the tool over the coming weeks, we'll add ways to filter the results down, to attenuate some of the 'interpretation noise'. It's interesting to think about ways to represent this result — what is the 'true interpretation'? Is it the cloud of all opinions? Is there one answer?

Click here to visit the new site. For now it only plays nicely on a desktop computer (mobile is such a headache, but we will get there!). But you should be able to log in, interpret images, and upload new ones. You can let me know about bugs, or tweet @nowpickthis. If you like it, and I really hope you do, please tell your friends!

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A quick reminder about the hackathon in Vienna next month. It will be an intense weekend of learning about programming and building some fun projects. I hope you can come, and if you know any geos in central Europe, please let them know!

Moving ahead with social interpretation

After quietly launching Pick This — our social image interpretation tool — in February, we've been busily improving the tool and now we're moving into 2016 with a plan for world domination. I summed up the first year of development in one of the interpretation sessions at SEG 2015. Here's a 13-minute version of my talk:

In 2016 we'll be exploring ways to adapt the tool to in-house corporate use, mainly by adding encryption and private groups. This way, everyone with @awesome.com email addresses, say, would be connected to each other, and their stuff would only be shared among the group, not with the general public.

Some other functionality is on the list of things to do:

• Other types of interpretation than points, lines and polygons.
  
• Ways to find content more easily, for example with tags like 'Seismic' or 'Outcrop'.
  
• Ways to follow individuals, or get notifications of new interpretations on an image.
  
• More ways to visualize and generally get at the data Pick This produces.
  

We're always open to suggestions. Please get in touch if you have a neat idea!

Pick This again

Since I last wrote about it, Pick This! has matured. We have continued to improve the tool, which is a collaboration between Agile and the 100% awesome Steve Purves at Euclidity.

Here's some of the new stuff we've added:

• Multiple lines and polygons for each interpretation. This was a big limitation; now we can pick multiple fault sticks, say.
• 'Preshows', to show the interpreter some text or an image before they interpret. In beta, talk to us if you want to try it.
• Interpreter cohorts, with randomized selection, so we can conduct blind trials.  In beta, again, talk to us.
• Complete picking history, so we can replay the entire act of interpretation. Coming soon: new visualizations of results that use this data.

Some of this, such as replaying the entire picking event, is of interest to researchers who want to know how experts interpret images. Remotely sensed images — whether in geophysics, radiology, astronomy, or forensics — are almost always ambiguous. Look at these faults, for example. How many are there? Where are they exactly? Where are their tips?  

A seismic line from the Browse Basin, offshore western Australia. Data courtesy of CGG and the Virtual Seismic Atlas

Most of the challenges on the site are just fun challenges, but some — like the Browse Basin challenge, above — are part of an experiment by researchers Juan Alcalde and Clare Bond at the University of Aberdeen. Please help them with their research by taking part and making an interpretation! It would also be super if you could fill out your profile page — that will help Juan and Clare understand the results. 

If you're at the AAPG conference in Denver then you can win bonus points by stopping by Booth 404 to visit Juan and Clare. Ask them all about their fascinating research, and say hello from us!

While you're on the site, check out some of the other images — or upload one yourself! This one was a real eye-opener: time-lapse seismic reflections from the water column, revealing dynamic thermohaline stratification. Can you pick this?

Pick This challenge showing time-lapse frames from a marine 3D. The seabed is shown in blue at the bottom of the images.