Chemically Enhanced Carbon Dioxide Geosequestration Using Nanofluids

Carbon dioxide (CO) sequestration in the subsurface porous geological media is the most favored large-scale climate change mitigation technique to achieve a net-zero target. The efficiency of CO subsurface storage depends on its rock's wetting ability, which affects its flow efficiency and residual or structural trapping. Reported laboratory investigations have shown that nanoparticle formulations have great potential for altering the wettability to more water-wet conditions favoring CO trapping potential. However, the compatible nanoparticles tailored for CO sequestration under temperature, pressure, and salinity conditions have not been reported, as per our knowledge. Therefore, this article demonstrates how modified silica nanoparticles affect the rock's surface and help enhance CO trapping potential under storage conditions using wettability, IFT, and CT coreflooding experiments. Several silica nanoparticles were fabricated for this purpose. The fabricated silica nanoparticles were modified, given the unfavorable formation brine salinity and ionic compositions affecting their stability. The resulting modified silica nanoparticles were diluted to 0.5 wt% with synthetic brine and observed for brine resistance at 50 °C for one month. They were further tested for wettability alteration of the organic acid-aged sandstone rock representative substrate in the presence of supercritical CO at 50 °C and 10 MPa by contact angle method. Furthermore, we evaluated their performance by computed tomography (CT) coreflooding experiments using Fontainebleau sandstone core plugs. These nanoparticles altered the wettability of the organic acid-aged sandstone rock representative substrate sample from intermediate wet (advancing brine contact angle - 90-108°) to strongly water wet (advancing brine contact angle - 33-49°). Modified silica nanoparticles also show high brine resistance. Therefore, up to 24.2% reductions in IFTs were observed using nanoparticles. Moreover, CT coreflooding test results shows good performance of novel nanofluids treatment on CO trapping potential through evaluation of initial and residual trapping. Therefore, up to 80.6 % and 55.8 % increments were observed using nanoparticles in initial and residual scCO saturations, respectively. We are reporting the use of novel modified silica nanoparticles for CO sequestration in sandstone formation for the first time, as per our knowledge. We expect these specialty nano-materials to enhance CO storage capacity through nanofluid injections as one of the emerging techniques for achieving net zero.