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The scale of a wavelet

It doesn’t take long to get accustomed to the ability to sit comfortably at a computer workstation and cruise around a subterranean world with just a few mouse clicks. The technology we use to observe, describe, and interpret subsurface geology is truly amazing. The advent of 3D seismic-reflection data coupled with immersive visualization software allows us to characterize and, importantly, to conceptualize the heterogeneity and dynamics of reservoirs.

With this power, it’s sometimes easy to forget the scale of geology we are deal­ing with in subsurface data. The scale of features combined with the type and resolution of data you are looking at can often lead to interpretations that do not capture the true complexity and heterogeneity.

I find it useful to constantly ask myself questions about scale when interpreting the subsurface: How thick is the package of interest? How wide is it? Take a few minutes and do the back-of-the-envelope calculations to see how many Empire State buildings (about 1 million cubic metres) or Calgary Saddledomes (250 000 cubic metres) fit inside your volume of interest.

Romans.jpg

When you figure out display settings that best work for you and the data you are characterizing, calculate the vertical exaggeration. Write this on a sticky note and attach it to your monitor. It’s quite common to view these data at high vertical exaggerations — especially in fields where subtle stratigraphic traps are the issue.

Finally, and most importantly, go on a field trip at least once every couple of years. Observing and pondering geology in the field has numerous intellectual benefits — far too many to list here. Seek out the extraordinary, like the tur­bidites onlapping the basin margin in the Eocene of the French Alps opposite. The realization of scale is among the most critical. Spending an hour or more trekking your way up a rocky slope to see some outcrops and then finding out all that expended energy and sweat got you through about half a wavelet is an unforgettable experience.


Acknowledgments
Image by the author. See ageo.co/LbQLUg for the full story.

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