I co-organize with Laurent Demanet
The intro to seismic imaging lectures I gave at MSRI are here and here .
Research Students Publications Teaching Personal
Each of my current research projects is described briefly below. If you're interested in my past work, have a look at my CV (pdf), for my guess at what I might be up to in the future, you can check out my
Multiply Scattered Coda, Interferometry, and Fracture Systems
Collaborators: Oleg Poliannikov, Gabi Melo and Mike Fehler from MIT and Michael Prange and Hugues Djikpesse of Schlumberger
Hybrid Imaging Techniques
Collaborators: Fernando Reitich , in the School of Mathematics at the University of Minnesota and James Greenleaf, Mostafa Fatemi , Thomas Gallot, MIT.
Ultrasound vibro-acoustography is a new imaging modality developed
at the Mayo Clinic that combines the high resolution possible with
high-frequency imaging methods with the clean (scatter-free) images
possible using low-frequency waves. It was first introduced by Fatemi
and Greenleaf in 1999; that paper can be
here . We are working to model these experiments with the goal of
improving the understanding of the underlying physics which we hope
will result in improved images of abnormal tissue. The image below
shows the current state of our model, on the left is an experimental
image of an aluminum rod submerged in water and on the right is the
result of our model for the same configuration. More details can be
found in the paper here .
Improving Illumination with Multiply-Scattered Waves
In typical seismic experiments for oil prospecting sources and
receivers are restricted to lie on the Earth's surface. Waves are
also typically assumed to reflect only once in the subsurface and to
travel primarily downwards into the Earth before reflecting and
upwards afterwards. The combination of these restrictions limits the
region of the Earth imaged. We are working to extend this region by
relaxing the restriction that waves scatter only once in the
subsurface. From doubly scattered waves this improves images of
steeply dipping structures and from triply scattered waves we are able
to image some structures from below. We have
published a theoretical paper and a
case study on this work, as well as two SEG abstracts. My
student Alan is working on a detailed comparison of our method with
The image below shows an example of imaging a fault, with a standard image
on the left and our improved image on the right; this example is
similar to that presented by Jin, Xu and Walraven at SEG in 2006,
available through the Society of
Focused Imaging for Detecting Changes
A 4D seismic data are used to monitor changes in a reservoir. A typical 4D data set consists of an initial data set collected before the change is made (baseline data) and one or more data sets collected during or after the induced change (monitor data sets). From these data, two images are typically made, one with the baseline data and the other with the monitor data set. Changes in the Earth are then estimated by subtracting the two resulting images. The changes are usually relatively isolated so this results in the processing of a lot of data that do are not sensitive to the changes we are interested in. We are working on both methods of estimating which parts of the data are most sensitive to changes, as discussed in Andrey's SEG abstract and on focused full-waveform inversion method, as discussed in Di's SEG abstract.
Starting Models for Full-Waveform Inversion
Collaborators: David Nicholls, of the University of Illinois at Chicago
Along with David Nicholls, I am working on methods to rapidly solve
the seismic inverse problem for layered media with independent
topography on each layer. We (mostly Dave) have done a lot of
preliminary algorithmic work available here
and here and are hoping to move on to data very
I am currently working with four students:
Gabi Melo is working on seismic interferometry between micro-seismic sources for geothermal energy, with limited receiver coverage.
Alan Richardson is working on combined imaging of multiples and primaries.
Andrey Shabelansky is working with Mike Fehler and I on developing imaging techniques for monitoring Steam Assisted Gravity Drainage.
Di Yang is working with Mike Fehler and I on developing full-waveform inversion methods for CO2 sequestration.
* Where the first author is not the primary or corresponding author of the paper, that author is marked with an asterix.