1. Travel-time Tomography For High Contrast Media based on Sparse Data Yenting Lin Signal and Image Processing Institute Department of Electrical Engineering University of Southern California February 3, 2013

2. Computed travel-time tomography is a powerful tool to produce tomographic image  Measure the signal response on the boundary  Slices of specific area of the object, Non-destructive detection  Widely used in geophysical and medical imaging Computed Travel-time Tomography

3. Problems Not enough data - samples may be expensive  Travel-time tomography in geophysical application: Very expensive to setup sensors, drilling costs much time and money  Under-determined nonlinear inverse problem High contrast structure  Some natural structure have high contrast property  Only need to separate the target structure and the background  Typical grid-based model and iterative reconstruction won’t work well in this case

4. Our work Reconstruct high contrast structure based on sparse travel-time data  Object based model – reduce the dimensionality  The solution is not unique - estimate the probability distribution of different models by randomized sampling techniques Object based model Grid based model

5. Water-flood tomography Apply our algorithm in petroleum application  Water is injected to support the pressure in the reservoir  Use well injection and production data to estimate the equivalent travel-time between well pairs  Estimate the high permeability areas in an oil field Probability map of high permGround truth in Simulator