A real-time autonomous adjusting process for fluid-fluid displacement in CO2 geological sequestration

To achieve net-zero carbon emission, securely and permanently sequestrating CO2 into deep underground is internationally assured as a robust solution, although a few technical challenges on complex in-situ storage process are yet to be overcome. Despite researchers are increasingly familiar with laboratory-scale CO2-brine displacement and how to characterize and improve the process, field implementation is not that simple and of great challenge. In this article, an opportunity on an approach that utilizes fluid-fluid displacement fundamentals is discussed to predict CO2 sequestration using artificial intelligence. A concept of machine learning is introduced, where computer programs can learn and improve automatically via previous experiences. With machine learning model, fluid displacement behaviors that are spontaneously monitored are emphasized to predict the displacement result, which is readily adjusted if needed while training the model from real-time CO2 injection response. Such an approach is a real-time autonomous adjusting process, consisting of three main stages: Selection of first appraisal fluid for trial injection, real-time machine learning from in-situ injection response, and fluid adjustment if needed or continuation on the same injection until achieving a maximum CO2 storage. This approach could play a vital role in the carbon capture and storage industry to develop CO2 storage effectively with adequate resources, and yet has a potential to substitute a conventional design or fluid screening approach for subsurface fluid injection, including underground hydrogen storage and hydrocarbon recovery.Cited as: Tangparitkul, S. M., Chantapakul, W., Promsuk, N. A real-time autonomous adjusting process for fluid-fluid displacement in CO2 geological sequestration. Advances in Geo-Energy Research, 2023, 7(2): 71-74. https://doi.org/10.46690/ager.2023.02.0

The effect of cationic surfactants on improving natural clinoptilolite for the flotation of cesium

Flotation using cationic surfactants has been investigated as a rapid separation technique to dewater clinoptilolite ion exchange resins, for the decontamination of radioactive cesium ions (Cs+) from nuclear waste effluent. Initial kinetic and equilibrium adsorption studies of cesium, suggested the large surface area to volume ratio of the fine zeolite contributed to fast adsorption kinetics and high capacities (qc = 158.3 mg/g). Adsorption of ethylhexadecyldimethylammonium bromide (EHDa-Br) and cetylpyridinium chloride (CPC) surfactant collectors onto both clean and 5 ppm Cs+ contaminated clinoptilolite was then measured, where distribution coefficients (Kd) as high as 10,000 mL/g were evident with moderate concentrations CPC. Measurements of particle sizes confirmed that adsorption of surfactant monolayers did not lead to significant aggregation of the clinoptilolite, while 4, highlighting the great viability of flotation to separate and concentrate the contaminated powder in the froth phase

Discontinuous dewetting dynamics of highly viscous droplets on chemically heterogeneous substrates

Hypothesis Droplet spreading on heterogeneous (chemical/structural) surfaces has revealed local disturbances that affect the advancing contact line. With droplet dewetting being less studied, we hypothesize that a receding droplet can be perturbed by localized heterogeneity which leads to irregular and discontinuous dewetting of the substrate. Experiments The sessile drop method was used to study droplet dewetting at a wettability boundary. One-half of a hydrophilic surface was hydrophobically modified with either i) methyloctyldichlorosilane or ii) clustered macromolecules. A Lattice Boltzmann method (LBM) simulation was also developed to determine the effect of contact angle hysteresis and boundary conditions on the droplet dynamics. Findings The two surface treatments were optimized to produce comparable water wetting characteristics. With a negative Gibbs free energy on the hydrophilic-half, the oil droplet receded to the hydrophobic-half. On the silanized surface, the droplet was pinned and the resultant droplet shape was a distorted spherical cap, having receded uniformly on the unmodified surface. Modifying the surface with clustered macromolecules, the droplet receded slightly to form a spherical cap. However, droplet recession was non-uniform and daughter droplets formed near the wettability boundary. The LBM simulation revealed that daughter droplets formed when > 164°, with the final droplet shape accurately described by imposing a diffuse wettability boundary condition

Competitive Adsorption of Interfacially Active Nanoparticles and Anionic Surfactant at the Crude Oil–Water Interface

The interfacial activity of poly(N-isopropylacrylamide) (pNIPAM) nanoparticles in the absence and presence of an anionic surfactant (sodium dodecyl sulfate, SDS) was studied at a crude oil–water interface. Both species are interfacially active and can lower the interfacial tension, but when mixed together, the interfacial composition was found to depend on the aging time and total component concentration. With the total component concentration less than 0.005 wt %, the reduced interfacial tension by pNIPAM was greater than SDS; thus, pNIPAM has a greater affinity to partition at the crude oil–water interface. However, the lower molecular weight (smaller molecule) of SDS compared to pNIPAM meant that it rapidly partitioned at the oil–water interface. When mixed, the interfacial composition was more SDS-like for low total component concentrations (≤ 0.001 wt %), while above, the interfacial composition was more pNIPAM-like, similar to the single component response. Applying a weighted arithmetic mean approach, the surface-active contribution (%) could be approximated for each component, pNIPAM and SDS. Even though SDS rapidly partitioned at the oil–water interface, it was shown to be displaced by the pNIPAM nanoparticles, and for the highest total component concentration, pNIPAM nanoparticles were predominantly contributing to the reduced oil–water interfacial tension. These findings have implications for the design and performance of fluids that are used to enhance crude oil production from reservoirs, particularly highlighting the aging time and component concentration effects to modify interfacial tensions

Interfacial behavior of core–shell composite nanoparticles under compression and shear: Influence of polymer shell thickness

Hypothesis The mobility of core–shell nanoparticles partitioned at an air–water interface is strongly governed by the compliance of the polymer shell. Experiments The compressional, relaxation and shear responses of two polymer-coated silica nanoparticles (CPs) were studied using a Langmuir trough and needle interfacial shear rheometer, and the corresponding structures of the particle-laden interfaces were visualized using Brewster angle and scanning electron microscopy. Findings The mobility of CPs partitioned at an air–water interface correlates to the polymer MW. In compression, the CPs40-laden interface (silica nanoparticles coated with 40 kDa PVP) showed distinct gas–liquid-solid phase transitions and when the surface pressure was reduced, the compressed particle-laden interface relaxed to its original state. The compressed-state of the CPs8-laden interface did not relax, and wrinkles in the particle-laden film that had formed in compression remained due to greater adhesion between the compressed particles. The increased mobility of the CPs40-laden interface translated to lower surface shear moduli, with the viscoelastic moduli an order of magnitude or more lower in the CPs40-laden interface than the CPs8-laden interface. Ultimately this contributed to changing the stability of particle-stabilized foams, with less mobile interfaces providing improved foam stability

Dewetting dynamics of heavy crude oil droplet in low-salinity fluids at elevated pressures and temperatures

Hypothesis Improved oil recovery by low-salinity injection correlates to the optimal brine concentration to achieve maximum dewetting of oil droplets on rock surfaces. While interfacial tension and electrical double layer forces are often cited as being determinant properties, we hypothesize that other structural/interfacial forces are more prominent in governing the system behavior. Experiments The sessile droplet technique was used to study the receding dynamics of oil droplets from flat hydrophilic substrates in brines of different salt type (NaCl and CaCl2) and concentration, and were studied at both low and elevated temperatures (60 and 140 °C) and pressures (1, 10, 100 and 200 bar). Findings At 1 bar and 60 °C, the minimum oil droplet-substrate adhesion force () was determined at 34 mM NaCl and 225 mM CaCl2. For NaCl this strongly correlated to strengthening hydration forces, which for CaCl2 were diminished by long-range hydrophobic forces. These results highlight the importance of other non-DLVO forces governing the dewetting dynamics of heavy crude oil droplets. At 140 °C and 200 bar, the optimal brine concentrations were found to be much higher (1027 mM NaCl and 541 mM CaCl2), with higher concentrations likely attributed to weakening hydration forces at elevated temperatures

Molecular Survey of Strongly and Weakly Interfacially Active Asphaltenes: An Intermolecular Force Field Approach

Subfractionation of asphaltenes based on their interfacial activity has begun to highlight critical differences between those asphaltenes that are strongly interfacially active (IAA) and the remaining asphaltenes (RA). Following the methods of petroleomics, representative structures of the two asphaltene fractions were determined, reflecting differences in abundant heteroatom groups, carbon number, double-bond equivalents, and single-core/multicore motifs. Using atomistic-potential-based grid-search methods, the intermolecular interactions between asphaltene–asphaltene and asphaltene–solvent (water, heptane, and toluene) were rapidly screened to identify the most favorable and therefore most likely intermolecular interactions to occur. Asphaltene–water interactions were stronger for IAA (abundance-weighted average interaction energy of −9.29 kJ/mol) than for RA (−6.32 kJ/mol), with hydrogen bonding more significant in the IAA–H2O interaction. Dimer interactions of IAA–IAA were stronger than RA–RA, and from the top 100 most favored interactions, the contribution to the total interaction energy was almost exclusively van der Waals for RA–RA (only 3% electrostatic), while for IAA–IAA, electrostatic interactions (9%) and hydrogen bonding (2%) were significant contributors in the most favored interactions. As the relative contribution of the electrostatic interaction increased, the dimer orientation less resembled that of a π–π stack. With the conception of petroleomics and large structural databases, the grid-search method is a useful atomic/molecular screening approach that provides an ideal triaging tool to rapidly assess a wide range of different molecular structures and interactions. The method is complementary to the more computationally expensive precision molecular modeling tools that are not suited to such workflows