Erosional valleys at a major Late Jurassic–Early Cretaceous unconformity offshore Germany and The Netherlands: potential reservoirs or deteriorated seals?

Abstract

AbstractJoint results of two independent international studies on the erosional impact of the ‘Late Cimmerian Unconformity’ (LCU), a Late Jurassic–Early Cretaceous erosional event, are presented. The potential impact on the reservoir and sealing potential of adjacent strata are discussed. Results are based on a seismic mapping campaign in the NE part of the Dutch offshore region and the Central German North Sea sector. The geological evolution of potential traps at the level of the LCU was studied to obtain a better understanding of reservoir potential. Erosion or leaching of the evaporitic Triassic intervals at the LCU caused a locally strong topographical relief with prominent elongated depressions along Permian salt structures (interpreted as erosional valleys). The infill of the erosional valleys may consist of remnants of initial strata as breccia or material from nearby eroded strata, possibly Lower Triassic sandstone or clays. These valleys may be overlain conformably by Upper Jurassic–Early Cretaceous sediments or may be filled with a combination of both. The lithological composition of the infill determines the sealing or the reservoir potential of the valleys, which is essential for further evaluation of the resource exploration possibilities in this locality and across the basin.