Sulfonated lignin-based phenol–formaldehyde resin: stability and structure changes during aggregation

Phenol–formaldehyde resin can be used to improve oil recovery; its key lies in its aggregation behavior and blocking strength. However, the traditional phenol–formaldehyde resin used in the petroleum field is all prepared by phenol and formaldehyde. In order to get rid of the dependence on fossil resources and make full use of renewable biomass resources, we used the abandoned walnut shells of the unique agricultural and forestry crops in Gansu province, which contains lignin partially replaced phenol to synthesize the new sulfonated lignin-based phenol–formaldehyde resin (SLPFR). The results showed that the optimum conditions for microwave polymers were polystyrene substitution rate of 20 wt%, decomposition temperature of 160 ℃, decommissioning time of 20 min, and sodium hydroxide concentration of 0.3 mol/L. Infrared spectroscopes and scanning telescopes have shown that after disintegration, there was an increased concentration of phosphorus, which had more active spots and was more suitable for replacing phenylphenol-synthetic formaldehyde resins. LC–MS indicated the molecular mass of SLPFR and the possible structure of molecules, indicating the successful synthesis of SLPFR. In this work, the aggregation behavior and dispersion stability of SLPFR were investigated from the composition of formation water. The effects of metal cations (Na⁺, Mg²⁺, Ca²⁺) on the dispersion stability of SLPFR in formation water were determined by turbidimetry, and the effects of metal cations on the particle size and zeta potential of the SLPFR system were measured by dynamic light scattering method and electrophoretic light scattering method. The stability of the aggregate structure of the SLPFR system was calculated by combining the fractal dimension. In this paper, the surfactant + SLPFR system and partially hydrolyzed polyacrylamide (HPAM) + SLPFR system were designed for the specific conditions of oil reservoirs, and the effects of metal cations on the aggregation behavior and dispersion stability of these two systems were studied. Based on the above comprehensive analysis, aggregation models were constructed to describe the aggregation behavior and dispersion stability of the HPAM + surfactant + SLPFR system. This makes it possible to predict in real time the migration and plugging of SLPFR aggregates in formation water.

Graphical abstract