3D stratigraphic forward modeling of mixed carbonate-siliciclastic systems: Insights to energy prospectivity

A mixed siliciclastic and carbonate depositional system offers a unique opportunity to investigate the interaction between two competing systems, clastic influx, and carbonate factories. Our understanding of the primary controlling processes that govern the development of mixed systems throughout Earth's history remains debatable, particularly during greenhouse and icehouse worlds. To address these issues, we explored and evaluated different stratigraphic forward modeling (SFM) scenarios by varying the magnitude and frequency of eustatic sea level changes and sediment-water supply and discharge following the conditions during greenhouse and icehouse worlds. Our findings show that the spatiotemporal distribution of lithofacies, thickness, and sediment volume differ significantly between the two simulated models. In the icehouse model, the regressive phase is characterized by deep shelf incision but with a less pronounced progradation pattern and drastic shoreline movements. The greenhouse model, in contrast, results in widespread prograding sedimentation and frequent shoreline trajectory changes during the same phase. Carbonate sedimentation was characterized by distinct backstepping geometry formed during sea level rise in the startup stage and the varying carbonate thickness between the greenhouse and icehouse models. These simulated observations agree well with cases found globally in the mixed carbonate siliciclastic system, further supporting the potential of SFM for depicting and quantifying the input parameters on a mixed carbonate-siliciclastic system. The synthetic seismic modeling further confirms the morphological and amplitude characteristics of typical reservoir targets and seals in both icehouse and greenhouse system that could help the identification of these features in real-world seismic data. The findings suggest that a better understanding of mixed depositional systems in both the greenhouse and icehouse periods can aid in driving towards more sustainable energy exploration.