An Introduction to: Velocity Model Building

This book has its origins in the EAGE continuing education course on veloc- ity model building I first taught in 2009. The objective was to give participants an intuitive (rather than mathematical) understanding of the kinematics of migration and how we go about building a model of the earth's subsurface, in terms of velocity and anisotropic parameters for use in imaging seismic data. 'Ihe book expands on the original course material, assessing why a detailed model is needed, the conse- quences of not getting it right, the sources of uncertainty and the limits on resolu- tion in velocity model building. An historical overview of velocity model building techniques over the past 30 years is presented to give the reader a feel for how the black art of model building has evolved in tandem with the increase in computer power, and the emergence of powerful interactive graphics. The movement from ID vertical update to true 3D tomographic update is discussed, as is the evolution from a purely linear compartmentalized industrial process for velocity estimation and image creation, to a fully interactive multidisciplinary approach to iteratively building a reliable subsurface velocity model with prestack depth migration.