Based in Mahone Bay, nova scotia, agile libre is an independent publisher of technical books about the subsurface.  

Geology comes first

A new, high-quality, 3D seismic reflection survey arrives in the office on a portable drive, or is transferred from a service company via FTP. The big question is, ‘who should interpret the shiny new volume?’

Some companies believe that a geophysicist should interpret seismic data; seismic data is, after all, a geophysical data type, and geophysicists understand how such data are acquired and processed. They will understand the procedures used to depth-migrate the dataset and, perhaps, the steps that were undertaken to preserve amplitudes, correct statics, or suppress multiples. A geophysicist, however, may have no or only limited experience of the geological complexity that is present in the earth’s subsurface. They may never — or only rarely — have been into the field to look at fluvial channels, segmented normal faults, or carbonate build-ups. 

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How can a geophysicist therefore make sense of the spatially complex and typically subtle features that are visible in many modern 3D seismic reflection datasets?

Perhaps the solution to the problem is to let a geologist, with a robust understanding of both structural geology and stratigraphy, but with some training in geophysics, interpret the data. They will understand the styles of secondary deformation that may be associated with a series of passive margin toe-thrusts. They will understand how seismic-scale clinoforms can provide insights into palaeo-sea-level changes, and the implications of this for identifying intervals that may be associated with lowstand deep-water reservoirs.

Geologists may, of course, forget that they are looking at an acoustic image of the earth rather than an outcrop, and they may be prone to interpreting too much geology. But surely it makes sense to have this new 3D seismic volume interpreted by the person with the best three-dimensional understanding of the complex structure and stratigraphy that exists in the earth’s subsurface? 


Acknowledgments

Offshore Netherlands F3 dataset from the dGB Earth Sciences Open Seismic Repository, opendtect.org/osr.

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