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Phenol-formaldehyde resins combined with polymers have a wide range of industrial applications as plugging agents for profile control and enhanced oil recovery. Due to the structural resemblance between lignin and phenol, there are possibilities for environmentally friendly phenol-formaldehyde resin manufacturing. Sulfonated lignin–based phenol-formaldehyde resin was synthesized by partially replacing phenol with lignin, which improved the utilization rate of lignin and achieved the purpose of environmental preservation and resource conservation. Partially hydrolyzed polyacrylamide is the most widely used polymer in chemical methods for enhanced oil recovery. However, the stability of reservoirs with high salt and high temperatures is weak under these conditions. To solve the problem of low oil recovery in high-salt reservoir environments, polymer flooding is adopted, which utilizes high-molecular-weight polymers to raise the viscosity of injected fluids, thereby improving sweep efficiency and altering mobility ratio between oil and injected fluid. We focus on the stability study of different molecular weights partially hydrolyzed polyacrylamide combined with sulfonated lignin – based phenol-formaldehyde resins in metal ions and surfactants. The zeta potential and hydrodynamic diameter of the partially hydrolyzed polyacrylamide – sulfonated lignin – based phenol-formaldehyde resin system in Ca2+ were measured by dynamic light scattering and static light scattering, and the dispersion stability was analyzed. The interfacial energy – modified DLVO theory was introduced to evaluate the stability of its colloidal solution, which made it possible to predict the aggregation behavior of sulfonated lignin – based phenol-formaldehyde resin and the co-migration process of metal cations in real time. [ABSTRACT FROM AUTHOR]

Enhanced oil recovery research focuses on the phenol–formaldehyde resin (PFR) solution (EOR). We studied PFR's morphology and aggregation kinetics at various pH levels. A hydrated layer formed on the surface of PFR as a result of hydrogen bonding between the hydroxyl and phenolic hydroxyl groups and water molecules. We quantitatively quantified the impact of pH on the morphology and aggregation kinetics of PFR by incorporating the hydrated force into the DLVO (Derjaguin Landau Verwey Overbeek) theory. We were able to predict the situation of aggregates plugging into the reservoir by altering the size of PFR aggregates in a capillary. [ABSTRACT FROM AUTHOR]

The stability of phenol–formaldehyde resin (nHAP) in the oil displacement process influences its flooding and profile control capabilities. There aren't many studies that compare how various surfactants affect PFR stability. The surfactants CTAB, Tween 60, and SDS were selected as representative ones. To look at the changes in stability, spectral turbidity and dynamic light scattering experiments were employed. It was found that the cationic surfactant CTAB can connect with the surface of PFR, just as metal cations, lowering electrostatic repulsion and facilitating the aggregation of PFR composite molecules. Anionic and nonionic surfactants both have some degree of system stability stabilizing properties. When Tween 60 and SDS adsorbed on the surface of the PFR molecule formed a hydrogen bond network with the hydroxymethyl or phenolic hydroxyl group, for example by hydrogen bond interaction, the PFR molecule's dispersion stability was increased. The Tween 60 and PFR composite systems have bigger particle sizes in addition to being more stable. Additionally, the energy barrier of the Tween 60/PFR composite system is determined using the modified DLVO theory for Lewis acid–base hydration, and it is discovered to be consistent with the experimental findings. The findings demonstrate that the stability of the composite system can be impacted by changes in the hydrophilicity and hydrophobicity of the composite system. The findings demonstrate that the stability of the composite system can be impacted by changes in the hydrophilicity and hydrophobicity of the composite system. Understanding the co-migration of PFR and surface activity during oil displacement depends heavily on the data. [ABSTRACT FROM AUTHOR]

The anions in the phenol–formaldehyde resin colloid interact with the metal cations in the system to form aggregates with different fractal structures. In this study, Mg2+ and Na+ were studied. At low cationic concentrations, colloid aggregates with the reaction-limited colloidal aggregation (RLCA) mechanism, forming loose aggregates. At high cationic concentrations, colloid aggregates with the diffusion-limited cluster aggregation (DLCA) mechanism, forming dense aggregates. By establishing the triple-layer surface complexation model of phenol–formaldehyde resin, the similarities and differences in interfacial characteristics of phenol–formaldehyde resin under different valence metal cation solutions were explained. The establishment of the triple-layer surface complexation model of phenol–formaldehyde resin is helpful in understanding the change of the aggregation morphology of phenol–formaldehyde resin in the rock gap and groundwater environment, and the change of the colloid interface properties during the co-transport of aggregates and colloidal metal cations. [ABSTRACT FROM AUTHOR]

In recent years, phenol-formaldehyde resin (PFR) as a colloid plugging agent was extensively used in enhanced oil recovery. It has been popularly concerned that the influence of environment on the structure, migration and aggregation behavior of PFR. The classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory can explain the interaction potential between particles. However, the classical DLVO cannot explain differences when colloids aggregate in the same valence metal cation solution. In this work, the effects of ion specificity of divalent metal cations (i. e., Mg2 + and Ca2 +) on the aggregation rate, fractal dimension, zeta potential and the c ritical c oagulation c oncentration (CCC) of PFR were systematically studied by dynamic light scattering experiment, electrophoretic light scattering and spectral turbidimetry. The experimental results showed that metal cations with poor hydration (i. e., Mg2 +) can promote aggregation more than metal cations with good hydration (i. e., Ca2 +). The hydrated differences of ions can be explained quantitatively by the improved DLVO theory introducing Lewis acid-base interaction. This result revealed the important significance of ion specificity in the aggregation behavior of PFR colloids, and made it possible to understand the co-transport process of PFR aggregates and metal cations in reservoirs. Thus, it is possible to precisely control the aggregation rate and the fractal dimension of PFR aggregates. [Display omitted] • Phenol-formaldehyde resin was prepared by adding NaOH step by step. • The aggregation kinetics of Phenol-formaldehyde were studied by turbidities. • We studied morphology of aggregates of Phenol-formaldehyde by fractal dimension. • Based on the DLVO theory, We proposed the interface energy of the colloid. • We explained differences of divalent ions by Lewis acid-base interaction. [ABSTRACT FROM AUTHOR]