On the tectono-stratigraphic evolution and hydrocarbon systems of extensional back-arc basins: inferences from 2D basin modelling from the Pannonian basin

Abstract

Two-dimensional basin modelling was carried out in the Pannonian basin of Central Europe to investigate the Miocene extension, post-rift evolution, and subsequent basin inversion and associated sedimentation. A tectono-sedimentary evolutionary model was constrained by seismic and well data. The simulated basin and petroleum systems model performed with petroleum systems modelling software package integrates the spatial and temporal variations of episodes of subsidence and uplift, sedimentation and erosion, and the dynamics of biogenic and thermogenic gas generation, migration, accumulation and loss. This high-resolution approach analysed the impact of the shelf-margin slope progradation and sequential sediment loading on mechanical compaction, pore pressure development, source rock maturation and hydrocarbon charge. Generation and migration processes were genetically controlled by the deposition of the SSE-ward prograding Pannonian (s.l.) shelf-margin slope sediments, and repeated tectonic inversions along the Mid-Hungarian Fault Zone. We tested different maturation kinetic models and compared the impact of different generation reaction schemes on charge. Biogenic gas generation was associated with the deposition of almost the entire sedimentary succession in the studied Jaszsag and Bekes sub-basins. However, the preservation of the gases was limited in time and space. Most of the thermogenic gas was generated by the deepwater marls in the Bekes sub-basin, whereas the depocentre of the Jaszsag sub-basin, mainly filled with Miocene rhyolites or rhyolitic tuffs connected to the intense volcanic activity, prevented the generation of significant amounts of hydrocarbon there.