New workflow for automating seismic interpretations and PSM studies

Migris AS and Seismic Partner AS have teamed up to apply a new workflow for automating seismic interpretations and PSM (Petroleum System Modelling) studies. The aim has been to create a next generation charge and risk model within the study area. The results from this study have now been made available for the industry. We use a data set containing 3D seismic over most of Quadrant 35 in the Norwegian North Sea in combination with the state-of-art Quad35 Hybrid MC3D 2020 Lumiseis 3D as input.

The workflow used automatic interpretation from the PaleoScan^TM software that yielded 200 interpreted horizons. The 50 most important horizons were used to build a TWT model in the Migri PSM software. The result is a new generation of models with many layers, which improves the quantitative description of the basin. Stratigraphy and lithologies from well logs have been selected to describe the layers by lithology fractions (e.g. Vsh). Formation tops from wells have been used to fine-tune the depth model after the depth conversion. The resulting high-resolution model (ca 39 million structural elements for 100m lateral resolution with 50 layers) was used as input to the Migri automatic iterative stochastic calibration of maturities, generation, and HC charge (migration) into traps (see Figure 1). The simulation runs were weighted against observations (Vitrinite and oil and gas column heights in wells) and then compiled into probability distributions that can be used to estimate trap and prospect HC filling uncertainties. This allowed for plotting Migri Flowrisk maps showing areas with high or low HC migration risk and Phaserisk maps to identify areas more likely to be charged with liquid hydrocarbons.

We used the opportunity to compare simulation results from 100, 200, 400 and 800 m lateral resolution models and were able to conclude that in this study area the results of the 2 high-resolution models were close over most of the study area.

***Figure:*** Complex charge of Jurassic and Cretaceous carriers within Quadrant 35 in the Northern North Sea (time step from 2 to 0 Ma). Black lines show layer boundaries from seabed down to Triassic. Green colours show oil migration and trapping. Yellow and red colours represent gas migration and trapping while blue colours show areas with mixed oil and gas migration. This figure was also presented at the DigX conference.

Overall, the workflow has uniquely enabled a regional calibration of the seismic interpretation and the petroleum system as a basis for a very detailed charge risk analysis in prospective zones of the study area. Fewer geological compromises have been needed than in previous workflows and the time required to perform the full analysis is strongly reduced. Parts of the methodology was presented at the well-attended DigX Subsurface 2024 conference (Sylta and Tømmerås, 2024).

For more information contact Øyvind Sylta at sylta@migris.no.