Migration Velocity Analysis.
Interim rept. Jan-Mar 95,
COLORADO SCHOOL OF MINES GOLDEN CENTER FOR WAVE PHENOMENA
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This thesis addresses the development of a general, quantitative representation between the imaged depths and migration velocity. Based on ray theory, I have found that the migration process can be described by using the so-called imaging equations. From this viewpoint, I have studied relationships between the residual moveout and the error of migration velocity in a general context. To handle lateral velocity variations, I used a perturbation method to derive an analytical formula to iteratively update the velocity from residual moveout. My formula estimates the update in velocity by computing a derivative function of imaged depths with respect to velocity in a general background medium context. This formula is more accurate than conventional formulas based on hyperbolic residual moveout when the medium has strongly lateral velocity variations. In addition, I discuss the sensitivity of migration-based velocity analysis, and show what factors affect the sensitivity. The theory and formulas developed here are available both for the 2-D case and for the 3-D case. The methodology in this thesis have been tested on synthetic data including the Marmousi data and on physical-tank data that are recorded in a scaled earth model.
- Numerical Mathematics