Impact of nanoparticles-surfactant solutions on carbon dioxide and methane wettabilities of organic-rich shale and CO2/brine interfacial tension: Implication for carbon geosequestration

Rock wetting behaviour and CO2/brine interfacial tension (IFT) have significant impacts on enhanced hydrocarbon recovery (EOR) and carbon geo-sequestration (CGS) projects. Influence of nanoparti-cles/surfactant solutions (NPS) flooding on EOR and CGS in sandstone and carbonate formation have been examined in recent studies. But the impact of NPS on carbon dioxide (CO2) and methane (CH4) wettabilities of organic-rich shale and CO2/brine IFT is presently unclear. Thus, we measured contact angles, [advancing (Oa) and receding (Or)] for CO2/brine and CH4/brine on Marcellus shale with high total organic carbon (14.8 wt%), as well as CO2/brine IFT with Kruss drop shape analyzer (DSA 100) through the sessile drop and pendant drop techniques. Prior to IFT and contact angles measurement, the shale samples were aged in NPS solutions to evaluate the impact of NPS treatment on CO2 geo-storage. Low-cost rice husk silica nanoparticles and saponin surfactant were used for the study due to their environmental friendliness and economic attractiveness. At geo-storage conditions (25 MPa and 353 K), the advancing contact angle of untreated shale was measured as Oa = 116.22 degrees (CO2- wet condition), whereas the receding contact angle was measured as Or = 82.88 degrees (near neutral wettability). However, Oa reduced by 56.34 degrees whereas Or reduced by 56.76 degrees when the shale substrate was treated with 0.1 wt% SiO2 and 0. 2 wt% saponin solutions. CO2/NPS IFT were lower than CO2/brine IFT and the CH4 wettability of the Marcellus shale was significantly lower than the CO2 wettability at all investigated conditions. Contact angles decreased with temperature and increased with CO2/CH4 pressure, whereas CO2/NPS IFT exhibited an opposite trend. The reduction in contact angles and CO2/brine IFT by NPS have significant impacts on adsorption trapping of CO2 in organic-rich shale and hydrocarbon recovery from unconventional shale reservoirs.(c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).