The Impact of Reverse Time Migration on the Evaluation of Mature Southern North Sea Assets

A case study is presented on the impact of Reverse Time Migration (RTM) on the derivation of a geologically realistic velocity model in a depth imaging sequence applied to a field development in the Southern North Sea. Exceptionally complex salt overhangs in the area make imaging of the Rotliegend target particularly challenging and despite repeated applications of the depth imaging technique since the mid 90’s, with the most recent one carried out in 2008, it has remained challenging to define the reservoir compartmentalisation and reconcile mapped GIIP volumes with well production profiles. The present interpretive processing workflow, with the application of state-of-the-art RTM in the velocity model building stage and a close cooperation of interpreters and depth imagers, has improved the imaging particularly below salt overhangs, yielded a geologically plausible model of the reservoir structure and offered new options for development well placement.