Fast 3D wave-equation migration-velocity analysis using the prestack exploding-reflector model

An accurate depth-velocity model is the key for obtaining good quality and reliable depth images in areas of complex geology. In such areas, velocity-model definition should use methods that describe the complexity of wavefield propagation, such as focusing and defocus ing, multiple arrivals, and frequency-dependent velocity sensitivity. Wave-equation tomography in the image space has the ability to ha ndle these issues because it uses wavefields as carriers of information. However, its high cost and low flexibility for parametrizing t he model space has prevented its routine industrial use. This thesis aims at overcoming those limitations by using new wavefields as carriers of information: the image-space generalized wavef ields. These wavefields are synthesized by using a pre-stack generalization of the exploding-reflector model. Cost of wave-equation tom ography in the image space is