CO2 capture and storage (CCS) is likely to become a necessary option in mitigating global climate change. However, lack of detailed knowledge on potential deep geological reservoirs can hamper the development of CCS. In this paper a new methodology is presented to assess and create exploration priority lists for poorly known reservoirs. Geological expert judgements are used as a basis in a two-stage geotechno-economic approach, where first an estimate of the practical reservoir capacity is calculated, and secondly source–sink matching is used for calculating an estimate of the matched capacity and the reservoir development probability. This approach is applied to Belgium, demonstrating how a priority ranking for reservoirs can be obtained based on limited available data and large uncertainties. The results show the Neeroeteren Formation as the most prospective reservoir, followed by the Buntsandstein Formation and the Dinantian reservoirs. The findings indicate that CO2 export to reservoirs in neighbouring countries seems inevitable; still, there is a 70% chance storage will happen in Belgian reservoirs, with an average matched capacity estimate of 110 Mt CO2 . These quantitative results confirm the qualitative resource pyramid classification of potential reservoirs. For Belgium, a high economic risk is attached to reservoir exploration and development. Exploration remains however a necessity if CCS is to be deployed. Furthermore, it is shown that the presented methodology is indeed capable of producing realistic results, and that using expert judgements for reservoir assessments is valid and beneficial.
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It is revealed that the lowest 1010 m of the Saint-Ghislain borehole (-4393 to -5403 m), of which cuttings are available, constitutes a crucial source of information to investigate, amongst others, the deep geothermal potential within the Brabant Parautochthon, underlying the Mons Basin, Hainaut. The lithological succession of this interval was reconstructed based mainly on visual analysis and calcimetry of 852 cutting samples as well as four core samples. Additionally, palynological, magnetic susceptibility and X-ray diffraction analyses were conducted in order to complement the dataset. The lower section of the investigated borehole sequence mainly consists of grey calcareous shale while the middle section is dominated by blue-grey shaly limestone and the upper section is mainly composed of green shale. Palynomorphs found at -5261 m suggest an uppermost Givetian–Lower Frasnian age. A new lithostratigraphical interpretation of the deepest part of the Saint-Ghislain borehole is proposed. The lower calcareous shale from -5403 m to -5100 m is interpreted as the Bovesse Formation (Lower Frasnian) and at its base possibly uppermost Givetian. The overlying limestones from -5100 to -4790 m can be attributed to the Rhisnes Formation (Upper Frasnian), and the green shale between ca. -4393 and -4790 m, to the Bois de la Rocq Member (Famennian). These results open new insights regarding the geological interpretation of the basement underlying the Mons Basin. They also present a promising approach and example regarding interpretations based on cuttings. KEYWORDS: Brabant Parautochthon, Mons Basin, Frasnian, Famennian, geothermal energy, Saint-Ghislain borehole
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RBINS Staff Publications 2020
