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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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