3D reservoir quality estimation of the Lower Volpriehausen Unit in the Eastern German North Sea: A statistic and stochastic modelling approach

Abstract

Carbon dioxide (CO₂) storage in deeply buried sandstones can contribute to the mitigation of greenhouse gas emissions, particularly from hard-to-abate industrial sectors. Triassic sandstones of the Middle Buntsandstein Subgroup on the West Schleswig Block offer favourable conditions to act as potential storage reservoir. While previous studies focused on regional assessments of trap structures and static capacity estimations, this is the first assessment of the extent and quality of the reservoir itself. We have created a 3D model of the West Schleswig Block to assess the reservoir quality and spatial distribution of the basal sandstones of the Volpriehausen Formation, the primary reservoir of the Middle Buntsandstein Subgroup in this region, at top depths between 2121 m (P10) and 2854 m (P90). To this end, we have developed parameter models for shale content, effective porosity, and permeability to obtain regional trend maps. Our results show that the Lower Volpriehausen Unit exhibit good lateral continuity, with a median thickness of 43 m (ranging from 25 m to 85 m) and a mean porosity of 21 % (12 % - 28 %, P10-P90). Locally, low porosities are primarily caused by high shale content and diagenetic cementation. These findings indicate variable reservoir quality for formerly mapped reservoir structures on the West Schleswig Block, which has to be considered in future carbon storage exploration efforts. Our study can facilitate future developments in the screening and evaluation of potential storage sites in the German North Sea and presents a valuable resource for local CO₂ storage capacity models.