Slip-tendency analysis of a potential CO2 storage site in the central German North Sea

TL;DR

This study assesses the seismic risk of CO2 storage in the German North Sea by analyzing fault reactivation potential using 3D fault data, stress modeling, and slip-tendency analysis, identifying faults with higher reactivation likelihood.

Contribution

It introduces a comprehensive 3D fault dataset and applies slip-tendency analysis to evaluate fault reactivation risk for CO2 storage sites in the North Sea.

Findings

NW/SE and NNW/SSE faults show higher slip tendency.

Faults with combined high slip tendency and potential magnitude identified.

Results inform risk assessment for underground CO2 storage.

Abstract

Underground CO2 storage operations may lead to induced seismicity, which can be partially related to nearby affected faults. Considering the storage potential in the Middle Buntsandstein sandstone formation on the West Schleswig Block within the German North Sea, we investigate the reactivation and seismicity potential of existing faults in the vicinity of a selected study area. For this, we develop a 3D fault data set based on roughly 80 2D seismic lines, combining 60 years of exploration history. Contextual details regarding the geological features and the lithological description of the area are presented. Using the fault data set and the present-day stress tensors derived through spatial interpolation of the 3D numerical stress model of Germany, a slip-tendency analysis is performed to assess the susceptibility of existing faults to reactivation and reveal critical focal mechanisms, which are important for further wave propagation simulation. Furthermore, we extend the procedure to estimate the sustainable pore pressure window and the potential moment magnitude in the event of a reactivation. The results show that the NW/SE and NNW/SSE-oriented faults exhibit a higher slip tendency. Among these faults, those with a combination of above-average slip tendency and potential moment magnitude are identified and discussed.