Potential for CO2 sequestration in saline formations in the western offshore Netherlands: A preliminary study-Expanding carbon capture and storage beyond depleted fields

Against the background of anthropogenic climate change and the need to mitigate CO2 emissions, the Netherlands is planning for industrial-scale carbon capture and storage in depleted gas fields, where a total practical storage capacity of approximately 1600 Mt is estimated to be available. At present, neither govern-ment nor industry have initiated plans for carbon capture and storage in saline formations, and to investigate other storage can-didates, we initiated a study of the geological potential for sequestering CO2 in saline formations in a part of the western Dutch offshore. We identified possible target formations in the Upper Jurassic and Lower Cretaceous fluvial to shoreface sand-stones and lower Paleogene shallow-marine sandstones in the West Netherlands Basin and Broad Fourteens Basin, located close to the industrial areas near Amsterdam. Three-dimensional seismic data show that the most promising trapping geometries exist in synclinal structures involving the Lower Cretaceous Vlieland Sandstone Formation, which formed during Late Cre-taceous inversion folding. Several scenarios suggest large pore volume space to be available in the subsurface below a depth of 800 m. We envisage that CO2 would be injected in the deeper parts of the target formation, from which it would migrate under buoyant flow until it reaches the seal and remains stratigraphi-cally trapped. The main risk identified so far relates to the seal integrity of basal Paleogene deposits, against which the storage formation is truncated in places. This academic research project (Deep Offshore Carbon Storage) will continue following the publication of this paper. The next phase will address studies on the seal integrity, reservoir efficiency, and economic feasibility.