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

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

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

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

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