North Sea Examples of Kirchhoff Least-squares Migration for Quantitative Interpretation

The biggest gas field in Western Europe is the Groningen field in the north of the Netherlands. Its production leads to a compaction of the Rotliegend reservoir which results in regional subsidence and earthquake activity. Detailed study of the detected events is required for assessing future induced seismicity hazards and risks. To locate an event, a moment tensor inversion method based on a full elastic waveform and an exhaustive grid search is employed. This approach necessitates the generation of a Green’s function database and, driven by the frequency content, requires a high-resolution velocity model. We describe herein key adaptations of the production workflow in order to handle both the resolution and Green function generation times requirements. Our solution uses of a full wave equation library making use of hybrid parallelism techniques. The results demonstrate an increase in the quality of the seismic event localization hand-in-hand with increased mesh resolution, leading to some of the largest elastic modeling runs performed in-house, to this date, and, to the second largest ones in the reported literature in terms of degrees of freedom