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Regularization of the AVO inverse problem by means of a ...

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2.3.6 Fatti’s approximation . . . . . . . . . . . . . . . . . . . . . . . . . . . 18<br />

2.4 Comparison <strong>of</strong> approximations . . . . . . . . . . . . . . . . . . . . . . . . . . 19<br />

2.5 Effect <strong>of</strong> γ = β<br />

α<br />

on forward modeling . . . . . . . . . . . . . . . . . . . . . . . 20<br />

2.6 Ray Tracing Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21<br />

2.6.1 Ray tracing method 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 21<br />

2.6.2 Ray tracing method 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 22<br />

2.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24<br />

3 Bayesian Inversion Approach and Algorithms 26<br />

3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26<br />

3.2 Bayes’ Theorem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26<br />

3.3 Prior distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27<br />

3.4 Inversion Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29<br />

3.4.1 Parameter selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33<br />

3.4.2 The least squares method . . . . . . . . . . . . . . . . . . . . . . . . . 34<br />

3.4.3 Weighted Least squares method . . . . . . . . . . . . . . . . . . . . . . 35<br />

3.4.4 Iterative re-weighed least squares method . . . . . . . . . . . . . . . . 35<br />

3.5 Target oriented <strong>AVO</strong> inversion . . . . . . . . . . . . . . . . . . . . . . . . . . 36<br />

3.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38<br />

4 Two-term <strong>AVO</strong> Inversion 39<br />

4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39<br />

4.2 Two-term <strong>AVO</strong> inversion formulation . . . . . . . . . . . . . . . . . . . . . . . 40<br />

4.2.1 Likelihood function <strong>of</strong> <strong>the</strong> data . . . . . . . . . . . . . . . . . . . . . . 41<br />

4.2.2 Multivariate Gaussian prior . . . . . . . . . . . . . . . . . . . . . . . . 42<br />

4.2.3 Univariate Cauchy prior . . . . . . . . . . . . . . . . . . . . . . . . . . 43<br />

4.2.4 Bivariate Cauchy prior . . . . . . . . . . . . . . . . . . . . . . . . . . . 45<br />

4.3 Syn<strong>the</strong>tic data examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

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