Practical And Fast Velocity Analysis By Multiple Pre-stack Time Migrations

Obtaining an accurate velocity model is fundamental to successfully imaging complex geologies. A practical and fast approach is developed to update the migration velocity model for improved imaging. It is achieved by analyzing the multiple migration sections in the control lines by scanning the migration velocity from 80% to 120% of the best available velocity models. The different percentages of the velocity model produce the reasonable or unreasonable, better or worse, imaging sections with varying degrees of clarity. The correct migration velocity can be estimated by integrating the right percentages of the velocity model, which produces the greatest improvement. Applying this approach to the real data shows that the estimated migration velocity reliably converges to the correct velocity. The CPU time consuming of the multiple migrations is not expensive, because multiple travel-time calculations for the different percentages of the velocity model are unnecessary.