Advancements in seismic imaging for geological carbon storage: Study of the Havnsø structure, Denmark

In Denmark, Geological Carbon Storage (GCS) has been prioritized as an immediate solution for climate action. The Havnsø domal structure has been identified as one of the most promising locations for GCS because its size and properties are believed to be suitable for GCS. However, the preliminary assessments, based mainly on old, sparse, and low-quality seismic data, are uncertain regarding the prospective storage resource and the integrity of the structure. To enable informed decisions and planning of the storage operations and as part of a large-scale acquisition campaign targeting several similar onshore structures throughout Denmark, a seismic data acquisition work was conducted in 2022 in the area. The purpose of the survey was to delineate the structural closure and map possible geologic features, such as faults, that could jeopardize GCS operations. In total, 132 km of high-fold and high-resolution 2D profiles were acquired using an innovative dual-element recording system for both deep and shallow subsurface imaging purposes. The recording comprises two vibrating sources and a combination of nodal recorders spaced at 10 m, and 2-m-spaced microelectromechanical systems (MEMS)-based recorders attached to a moving landstreamer. The seismic data contain information on all horizons of interest for GCS. The structure is estimated as a well-defined four-way closure, where the reservoir is continuous. A thick, mostly uniform sealing rock is interpreted and no large-scale faults are found in the near surface. The results, supported from existing background information, provide crucial information to assist further decisions and actions related to future storage operations in Havnsø.