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Residual migration velocity analysis
in the offset-depth domain via the ray parameter-depth domain
By Imtiaz Ahmed, Phillips Graduate Fellowship.
Abstract:
Over the last few decades, residual migration velocity analysis has been an area of active research. Previous works on residual migration velocity analysis in the depth-offset domain required top down layer stripping migration in order to derive the interval velocities directly, hence making it very computationally intensive. Here we propose a new technique in which for each common image gather (CIG) we first create a table of offset-ray parameters-depth (x-p-z) using a local 1D assumption. Then we calculate the residual migration depth corrections in the p-z domain and finally map these depth corrections back to the x-z domain using the x-p-z table. Since we calculate the residual migration depth corrections in the p-z domain, the interval velocities are derived directly by top down residual migration. Hence we do not have to explicitly do the layer stripping migration followed by residual normal moveout to get the interval velocities. Results on synthetic data are encouraging and real data tests are now being performed.
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