A comparative overview of velocity-independent imaging’s methods

Abstract

Relatively poor performance of full pre-stack migration in hard rock seismic exploration is related to our inability to produce accurate velocity field which, is caused by complicated structures, highly variable reflectivity, and low signal to noise ratio. That is why the estimation of velocities becomes a significant problem in hard-rock environment. Consequently we wish to use imaging approaches which are loosely dependent or completely independent of the knowledge of rock velocities. To get there, we review and analyse different velocity-independent imaging techniques developed over nearly past three decades. However, seismic imaging in complicated geological conditions often requires more than just one parameter such as accurate velocity field. Improvements of signal to noise ratio and data regularisation are typically necessary to enable construction of high resolution, high quality images. In such data, pre-conditioning should enable enhanced performance of velocity-less imaging techniques since their performance is critically dependent on input S/N ratio. The final approach, then, involves merging several techniques such are denoising, wave-field reconstruction/interpolation and velocity-independent tools together to improve image quality in hard-rock environment.