Abstract PFR combined with polymers have a wide range of industrial applications as plugging agents for profile control and EOR. Due to the structural resemblance between lignin and phenol, there are possibilities for environmentally friendly phenol-formaldehyde resin manufacturing. SLPFR 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. HPAM is the most widely used polymer in chemical methods for EOR. However, the stability of reservoirs with high salt and high temperature is weak under these conditions.To solve the problem of still low oil recovery in high-salt reservoir environments, polymer flooding is adopted, which utilises high molecular weight polymers to raise the viscosity of injected fluids, thereby improving sweep efficiency and altered mobility ratio between oil and injected fluid. We focus on the stability study of different molecular weight HPAM combined with SLPFR in metal ions and surfactants. The zeta potential and hydrodynamic diameter of HPAM-SLPFR system in Ca 2+ 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 SLPFR and the co-migration process of metal cations in real time.
To improve the stability and plugging property of low-solubility phenol formaldehyde resin (LPFR) in the injection water from Daqing Oilfield, hydrophobically associating polymers (HAP) as a stabilizing agent were used. The size and zeta potential of LPFR, LPFR/HAP molecule aggregates, and turbidity and plugging properties of LPFR dispersions were measured in deionized water, simulation water, and injection water, respectively. The results show that the hydrophobic grouping on the HAP molecule has a similar molecular structure as LPFR, and HAP and LPFR can form complex molecule aggregates in the injection water. The zeta potential of LPFR/HAP molecule aggregates is larger than that of LPFR molecule aggregates. Therefore, the repulsive force operating between LPFR/HAP complex molecule aggregates is increased. HAP enhances the stability of LPFR in the injection water and plugging property of LPFR dispersion in porous medium.
To study the effect of Tween 60 on dispersion property of water-soluble phenol-formaldehyde resin (PFR), the size and zeta potential of PFR/Tween 60 molecule aggregates and the surface tension, turbidity and blocking property of PFR/Tween 60 dispersion were measured. The results of the study show that when Tween 60 concentration in the PFR/Tween 60 solutions is lower than CMC, the dispersion property of PFR solution is not affected by Tween 60 significantly. When Tween 60 concentration in the PFR/Tween 60 solutions is higher than CMC, the Tween 60 molecules, and PFR molecules form complex molecule aggregates in water which affected the dispersion property of PFR solution significantly. The interaction between Tween 60 molecule and PFR molecule in the complex molecule aggregates is stronger than the interaction between PFR molecules in the PFR molecule aggregates.
To improve dispersion stability of water soluble phenol-fomaldehyde resin (PFR) in relatively low salinity water, the effect of hydrophobically associating polymer (HAP) on the dispersion property of PFR in NaCl solution was studied by the measurement of the size and zeta potential of PFR, HAP, and PFR/HAP molecule aggregates in NaCl solution, and the turbidity of PFR and PFR/HAP dispersions. The results show that due to the hydrophobically group on HAP molecule has similar structure as molecular structure of PFR and stronger hydrophobically association of HAP molecules in NaCl solution, HAP, and PFR molecules can form complex molecule aggregates together. The formation of the complex molecule aggregates enhanced the stability of PFR dispersion in NaCl solution.
Phenol formaldehyde resins (PFRs) as a colloidal oil displacement agent were commonly used to plug pores in crude oil reservoirs for enhanced oil recovery (EOR). The aggregation–dispersion and charging behavior of PFR may affect the rheology and plugging performance of the suspension. To understand the aggregation–dispersion and charge of PFR, turbidity, dynamic light scattering, and electrophoretic light scattering experiments were carried out at pH = 10 with different concentrations of salt solutions (NaCl, MgCl2, CaCl2, NaCl/MgCl2, and NaCl/CaCl2). The aggregation rate and ζ-potential were measured, and the critical coagulation concentration (CCC) and critical coagulation ionic strength (CCIS) were further obtained. Based on the triple-layer surface complexation (TL) model, the adsorption ability of cations and the surface characteristics of the PFR particles were studied, and these differences were explained by interface energy. Thus, Derjaguin–Landau and Verwey–Overbeek (DLVO) theory modified by interface energy was applied to explain the aggregation behavior of PFR particles in different types of ion systems. We concluded that, in the presence of multiple ions, DLVO theory modified by interface energy has good applicability to the aggregation–dispersion of PFR particles.
Abstract Carbon capture and storage (CCS) technology is a crucial means to address global climate change and reduce atmospheric CO2. CO2 mineralization storage can store CO2 in underground rock formations in a long-term and safe manner, which is the most stable storage method. However, this process may take several decades or even longer, severely constraining the application of CO2 mineralization storage in mining fields. In this work, we propose an innovative approach utilizing CO2 nanobubbles to achieve efficient CO2 mineralization. Chlorite was selected as the experimental sample to compare the effects of carbonated water and CO2 nanobubbles on CO2 storage. Analytical instruments were employed to analyze the rock surface morphology, mineral composition, and ion concentration in the reaction solution post-experiment, revealing the mechanism by which CO2 nanobubbles accelerate the CO2 mineralization rate. Results reveal that CO2 nanobubbles have an average size of 167.6 nm, a Zeta potential of −18.98 mV, and a concentration of 9.4×107 particles/mL. The solution's pH is lower than that of carbonated water, suggesting that the CO2 nanobubble solution enhances the supersaturation level of CO2 in the solution, which facilitates the dissolution of rock minerals. After the reaction of chlorite minerals with CO2, the concentrations of Mg2+, Fe2+, and Al3+ ions initially increased and then decreased, while the concentration of Si4+ ions increased and then stabilized. The ion content in the solution followed the order of Mg2+ > Fe2+ > Si4+ > Al3+. Dissolution processes dominate within the first 1 to 6 days, after which the precipitation rate surpasses the dissolution rate. The surface of chlorite exhibits corrosion features and a new element peak of carbon (C), indicating the formation of inorganic carbonate minerals after the reaction. Thermogravimetric analysis shows that the thermal decomposition of chlorite occurs in two stages: primarily MgCO3 decomposes between 350°C and 650°C, while FeCO3 decomposes between 700°C and 850°C, with a higher content of MgCO3 compared to FeCO3. Compared to carbonated water, the CO2 mineralization rate increased by 17.07% when the reaction solution contained CO2 nanobubbles. This approach can shorten the time required for CO2 mineralization storage, facilitating large-scale CO2 storage. Furthermore, the mechanism of CO2-water-rock interaction is also deeply revealed, which is of great value for understanding the underground CO2 storage process and optimizing the conditions for storage.
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