Assessment of the impact of CO2 storage in sandstone formations by experimental studies and geochemical modeling: The case of the Mesohellenic Trough, NW Greece

Abstract

Representative sandstone samples from Mesohellenic Trough (NW Greece) were selected to investigate the geochemical reactions that occur when they come in contact with CO 2 under representative in-situ conditions (T=70 o C, P=150bar, 6 months reaction in batch experiments). Those sandstones consisted of predominant calcite and quartz, with lesser amounts of feldspars, chlorite, ankerite, dolomite, kaolinite, montmorillonite and muscovite. After reaction with CO 2 , the brine became acidic and was enriched in cations as a result of mineral dissolution. Minor mineralogical changes were observed that involved: a) the dissolution of carbonate minerals and b) the incongruent dissolution of chlorite to form clays and silica. The results related to these, have been linked with geochemical modelling using the PHREEQC code. Simulation results for a 10 ka time period predicted that chlorite was expected to dissolve completely within 100 years, leading to boehmite growth and increasing the mass of dolomite. Feldspars were expected to react at a later stage in the reaction sequence. Sensitivity tests were run to access the effect of various adjustable parameters on the outcome results. The geochemical experiments and modelling lend support to the view that Pentalofos and Tsotyli sandstone formations of the Mesohellenic Trough are suitable for the long-term storage of CO 2 produced in the neighbouring lignite-fired power plants, at least in terms of mineralogy and geochemistry.

Petrographic Characteristics of Sandstones as a Basis to Evaluate Their Suitability in Construction and Energy Storage Applications. A Case Study from Klepa Nafpaktias (Central Western Greece)

“…These results show that the sandstones examined include relatively higher quartz contents and less calcite compared to those located in the Mesohellenic Trough [73]. Furthermore, effective porosity of the Klepa Nafpaktias sandstones, as it was calculated through the total porosity, which is about 6% for the Group I presents higher values of effective porosity in contrast to the other two sandstone groups and tend to be lower than the Pentalofos sandstones of the Mesohellenic Trough~9%.…”

“…This case presents many similarities with that described for the Mesohellenic Trough (NW Greece), which examined the potential of CO 2 storage within porous sandstones that are overlaid be a less permeable cap rock formation [71][72][73]. In the latter case, a depth of over 800 m was regarded as suitable for trapping CO 2 under supercritical conditions [73][74][75]. The sandstone samples provided from our study are highly comparable in terms of composition with sandstones from the Pentalofos formation of the Mesohellenic Trough [72].…”

“…This practically impermeable sedimentary formation lies stratigraphically above the sandstones, thus providing an excellent seal caprock to keep the buoyant CO 2 within the reservoir rock. This case presents many similarities with that described for the Mesohellenic Trough (NW Greece), which examined the potential of CO 2 storage within porous sandstones that are overlaid be a less permeable cap rock formation [71][72][73]. In the latter case, a depth of over 800 m was regarded as suitable for trapping CO 2 under supercritical conditions [73][74][75].…”

Carbon Capture and Storage: A Review of Mineral Storage of CO2 in Greece

“…Vatalis et al [73] proposed the storage of CO 2 in the known deposit of zeolite in Evros (Northern Greece). Koukouzas et al [74] concluded that the Pentalofos and Tsotyli sandstone formations could be a potential CO 2 storage site under specific conditions. This approach needs further investigation.…”

Carbon Capture and Storage. A Case Study of Mineral Storage of CO₂ in Greece

“…[66][67][68] Another deposit could be zeolite according to Vatalis 2012 69 and also the sandstone formations according to Koukouzas 2018. 70 Finally, it was investigated the role of water carbonation of forsterite in scCO2 and found that the reactions could be more extensive under specific conditions. 71…”