Abstract: A computer-implemented method for determining a velocity image of a domain of the subsurface structural geology in an oil and gas reservoir comprising an iterative method that combines a migration step and a population step propagating values from regions of the image wherein the velocity is known, or the velocity is according to information being deemed as correct. In this field of the technology this kind of data is also known as hard data. The iterative process uses a seismic image in depth of an initial guess as initial velocity model in a conjunction with tensor properties to generate a new velocity model based on criteria of minimum residual moveout on a specific point(s) or well control location(s). At these locations data information (velocity) is considered as well-known a-prior information to be propagated around the neighborhood guided taking into account the geological structure.

Abstract: The present invention is in the field of seismic imaging of underground structures. The invention is a method for solving the uncertainty and instability generated in reservoir geometries due to salt bodies which causes the presence of artifacts in the velocity fields. The method is based in a desalting process and a further specific reconstruction of the sediments located in the domain of the image. Desalting means to remove salt volumes located within the domain wherein said process is followed by the replacement of good sediment velocity values and a careful iterative process avoiding the generation of artifacts.