ABSTRACT
CO2 capture and storage in geological reservoirs have the potential to significantly mitigate the effects of anthropogenic gas emissions on global climate. Here, we report the results of the first laboratory experiments of CO2 injection in continental flood basalts of South America. The results show that the analyzed basalts have a mineral assemblage, texture and composition that efficiently allows a fast carbonate precipitation that starts 72 h after injection. Based on the availability of calcium, chemical monitoring indicates an estimated CO2 storage of ~ 75%. The carbonate precipitation led to the precipitation of aragonite (75.9%), dolomite (19.6%), and calcite (4.6%).
ABSTRACT
Clay minerals are abundant in caprock formations for anthropogenic storage sites for CO2, and they are potential capture materials for CO2 postcombustion sequestration. We investigate the response to CO2 exposure of dried fluorohectorite clay intercalated with Li+, Na+, Cs+, Ca2+, and Ba2+. By in situ powder X-ray diffraction, we demonstrate that fluorohectorite with Na+, Cs+, Ca2+, or Ba2+ does not swell in response to CO2 and that Li-fluorohectorite does swell. A linear uptake response is observed for Li-fluorohectorite by gravimetric adsorption, and we relate the adsorption to tightly bound residual water, which exposes adsorption sites within the interlayer. The experimental results are supported by DFT calculations.
ABSTRACT
Nanofluids have received a great deal of interest in recent years because of their various unique features. According to the findings, the addition of nanotubes to the base materials can drastically alter their properties. In the present work, the viscosity of a typical water-based nanofluid containing single-walled carbon nanotubes is estimated using the molecular dynamics simulation for different volume fractions ranging between 0.557 and 3% at two temperatures (298 K and 313 K). The temperature of the systems is controlled using a Nose-Hoover thermostat. For calculating viscosity, the Green-Kubo equilibrium method is used. The enthalpy, potential, kinetic, and total energies are calculated to determine the system's stability. In addition, the influence of molecular mass on these energies is studied. The nanotube under investigation is an armchair(6,6)-type single-walled carbon nanotube. The results highlight the promise of the molecular dynamics simulation technique as a powerful tool in the prediction of nanofluid properties besides the experimental results. The value of viscosity will decrease as the temperature rises, much like the base fluid. Furthermore, it is shown that the viscosity is proportional to the volume fraction of water-SWCNT nanofluid. According to the results, a new viscosity relationship for volume fractions in the range of Ï ≤ 3% is proposed. The viscosity, temperature, and volume fraction are all linked together in this equation.
ABSTRACT
Fluid flow through minerals pores occurs in underground aquifers, oil and shale gas reservoirs. In this work, we explore water and oil flow through silica nanopores. Our objective is to model the displacement of water and oil through a nanopore to mimic the fluid infiltration on geological nanoporous media and the displacement of oil with and without previous contact with water by water flooding to emulate an improved oil recovery process at nanoscale (NanoIOR). We have observed a barrier-less infiltration of water and oil on the empty (vacuum) simulated 4 nm diameter nanopores. For the water displacement with oil, we have obtained a critical pressure of 600 atm for the oil infiltration, and after the flow was steady, a water layer was still adsorbed to the surface, thus, hindering the direct contact of the oil with the surface. In addition, oil displacement with water was assessed, with and without an adsorbed water layer (AWL). Without the AWL, the pressure needed for oil infiltration was 5000 atm, whereas, with the AWL the infiltration was observed for pressures as low as 10 atm. Hence, the infiltration is greatly affected by the AWL, significantly lowering the critical pressure for oil displacement.
