A Robust High-resolution Time-lapse Simultaneous Joint Migration Inversion Process Applied to the Time-lapse Troll Field Datasets

We demonstrate the feasibility of a robust high-resolution Simultaneous Joint Migration Inversion (S-JMI) process as a tool for reservoir monitoring based on a 2D time-lapse field data example from the Troll field. Simultaneous Joint Migration and Inversion is an effective time-lapse tool for reservoir monitoring, which combines a joint time-lapse data processing strategy with the Joint Migration Inversion (JMI) method. In S-JMI, fine details are not expected in its inverted velocity model, as it only explains the propagation effects in the data, while the scattering effects are explained by the inverted reflectivity model. However, for time-lapse processing, high-resolution time-lapse velocity differences are usually a demand. Therefore, in order to get more localized time-lapse velocity differences, we choose to use a robust high-resolution S-JMI process by using the time-lapse reflectivity-difference as an extra constraint during S-JMI. This constraint makes a link between the reflectivity and the velocity-difference by exploiting the relationship between them, which can also be explained as a constraint on density. Finally, in the real data example, SJMI is able to reliably recover the time-lapse effects in the reflectivity model, and the velocity differences could also be reasonably well recovered, even though the repeatability of this datasets is not very good.