Hydrocarbon Migration Dynamics and Seal Integrity in the Flemish Pass Basin: Insights from Migration Modelling

Summary The Flemish Pass Basin, spanning over 10,000 km2, features sedimentary layers up to 10 km thick from the Mesozoic and Cenozoic eras. As part of the North Atlantic rift system, its tectonic history includes multiple rifting phases from the Triassic to Early Jurassic. Exploration efforts have focused on closures of rotated fault blocks, with varied success. The Late Tithonian and Lower Cretaceous synrift sandstone reservoirs show high porosity and permeability, while source rock intervals with type II kerogen offer good-to-excellent potential. The timing of hydrocarbon charge relative to the paleo-seal capacity of Cretaceous rocks is crucial for assessing the petroleum potential of the basin. A flow-path migration modelling tool evaluates scenarios involving reservoir charge, migration efficiency, lithological facies, net-to-gross maps, and seal capacity of Cretaceous and Jurassic sediments. This study examines how the sealing properties of these rocks over time impact hydrocarbon accumulation. Modelling results indicate a consistent pattern in the filling history of structures, with initial vertical hydrocarbon movement due to ineffective cap seals, followed by the establishment of effective seals. The timing of this transition varies across different structures in the basin. Discrepancies between modelled and observed accumulations highlight the need for refined input parameters and methodologies.