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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: What’s New in Seismic Imaging?
From a geophysicist’s perspective, the better the seismic image, the easier it is for the geologists to do their job. So in a sense, we are working hard to trivialize you! Of course in the hydrocarbon exploration and production business we’re collectively always working on the frontiers: geologically, geographically, technically, scientifically, etc. So our ability to image and interpret things we want to under s tand i s cons tant ly challenged. Do recent geophysical trends have the potential to revolutionize the relationship between geophysical data and geological understanding and interpretation of the interior of the Earth? Maybe. I’ll talk about these trends, which are the product of the incredible advances in computing power available for processing seismic data combined with clever thinking about how we collect seismic data.
For a variety of reasons, the deepwater region of the Gulf of Mexico is one of our favorite proving grounds for geophysical technologies. There, industry faces many technical challenges around developing subsalt reservoirs. A few years ago BP pioneered two new seismic acquisition methods that when coupled with advances in seismic processing have made substantial improvements in our understanding of these reservoirs. I’ll show you some examples of these methods applied to BP assets. One of the keys to motivating these advances was the use of seismic forward modeling. The ability to simulate realistic synthetic data and test hypotheses has become a critical part of geophysical science. We have even come to the point now where the same technology used to simulate data to the best of our ability is being used to process the data we actually acquire in the field. The future holds not only more clever ways of acquiring data, but ways of acquiring a lot more data.
If you hang around geophysicists enough, you’re certain to hear
them discuss “seismic velocities”. We need good estimates of the
speed that waves propagate in the subsurface to apply our imaging
methods. We take great pains to do this quickly and accurately.
However, many of the methods we used in the past are based on
substantial simplifications to the way waves
propagate. Recently, a method called
“Waveform Inversion” has been gathering a
lot of excitement. Historically the velocity
“models” that geophysicists have created were
lacking in information content at intermediate
scales. We could find sharp changes in
velocity
,
because they give rise to reflection events.
We could find very long wavelength trends in
the speed of wave propagation through
traveltime
tomography. Variations in wave speed
that were tens to a few hundred meters
in scale were not recovered. When we can
recover features with
velocity
expressions
at those scales, the results are dramatic in
terms of connecting geology to geophysics. I’ll
show some examples of this technology and explore its potential
for the future.
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