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Integrating Sensitivity Analysis and Igneous Activity Into Basin Modelling, Faroe-Shetland Basin, NE Atlantic

Abstract

Predicting hydrocarbon prospectivity in frontier, or under-explored basins, is inherently uncertain due to the limited data that are present. Even in areas with high density 2D, or indeed 3D, seismic reflection coverage the absence of well data across a basin significantly increases uncertainty in any petroleum system modeling. This limitation will become increasingly important as exploration focuses on Deep Water or Ultra-Deep Water settings. In this study we address this inherent uncertainty through integrated sensitivity analysis. The Faroe-Shetland Basin, NE Atlantic, presents a complex challenge to the process of basin modeling. The area is characterized by a complex poly-phase rift evolution, significant Cenozoic inversion and an extensive Paleogene volcanic system. In addition, well coverage is limited to the margins of the basin whilst the deep central and northwest portions remain un-drilled. Furthermore, seismic resolution deteriorates significantly with depth and around the expansive volcanic material resulting in significant uncertainty in the interpretation. In order to reduce uncertainty we perform sensitivity analysis on key modeling input parameters to define a best practice workflow for undertaking basin modeling in the Faroe-Shetland Basin and similar passive continental margin settings. The process allows us to categorize parameters based on their overall impact on the final model. By modeling four discrete 2D lines from across the basin we are able to constrain the variable heat flow history across the area and predict maturation whilst being able to define quantitatively the range of values. Our initial modeling focuses on the regional heat flow evolution and excludes any potential impact of the intrusive volcanic system. As the emplacement of igneous intrusions into sedimentary successions has been shown to locally elevate heat flow, we subsequently incorporate an expansive sill complex into the regional 2D modeling to investigate the cumulative effect of sequential sill emplacement on regional heat flow. Our results highlight the importance of determining the timing of emplacement and the volume of igneous material when assessing the potential impact on maturation and generation of hydrocarbons. Our workflow and results suggest that through an appraisal of sensitivity in areas of poor, limited or even absent data, such as frontier basins, we can derive a more constrained basin modeling approach that reduces exploration uncertainty.