Preparation of Multifunctional Surfactants Derived from Sodium Dodecylbenzene Sulfonate and Their Use in Oil-Field Chemistry

Synergistic Catalysis of Water-Soluble Exogenous Catalysts and Reservoir Minerals during the Aquathermolysis of Heavy Oil

Oil serves as the essential fuel and economic foundation of contemporary industry. However, the use of traditional light crude oil has exceeded its supply, making it challenging to meet the energy needs of humanity. Consequently, the extraction of heavy oil has become crucial in addressing this demand. This research focuses on the synthesis of several water-soluble catalysts that can work along with reservoir minerals to catalyze the hydrothermal cracking process of heavy oil. The goal is to effectively reduce the viscosity of heavy oil and lower the cost of its extraction. Based on the experimental findings, it was observed that when oil sample 1 underwent hydrothermal cracking at a temperature of 180 °C for a duration of 4 h, the amount of water added and catalyst used were 30% and 0.2% of the oil sample dosage, respectively. It was further discovered that the synthesized Mn(II)C was able to reduce the viscosity of oil sample 1 by 50.38%. The investigation revealed that the combination of Mn(II)C + K exhibited a significant synergistic catalytic impact on reducing viscosity. Initially, the viscosity reduction rate was 50.38%, which climbed to 61.02%. Subsequently, when catalyzed by the hydrogen supply agent isopropanol, the rate of viscosity reduction rose further to 91.22%. Several methods, such as freezing point analysis, thermogravimetric analysis, DSC analysis, component analysis, gas chromatography, wax crystal morphology analysis, and GC-MS analysis, were conducted on aqueous organic matter derived from heavy oil after undergoing different reaction systems. These analyses confirmed that the viscosity of the heavy oil was decreased. By studying the reaction mechanism of the model compound and analyzing the aqueous phase, the reaction largely involves depolymerization between macromolecules, breakdown of heteroatom chains, hydrogenation, ring opening, and other related consequences. These actions diminish the strength of the van der Waals force and hydrogen bond in the recombinant interval, impede the creation of a grid-like structure in heavy oil, and efficiently decrease its viscosity.

Enhanced Aquathermolysis of Water-Heavy Oil-Ethanol Catalyzed by B@Zn(II)L at Low Temperature

In order to study the synergistic effects of exogenous catalysts and in situ minerals in the reservoir during heavy oil aquathermolysis, in this paper, a series of simple supported transition metal complexes were prepared using sodium citrate, chloride salts and bentonite, and their catalytic viscosity reduction performances for heavy oil were investigated. Bentonite complex catalyst marked as B@Zn(II)L appears to be the most effective complex. B@Zn(II)L was characterized by scanning electron microscopy (SEM), Fourier-Transform Infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA) and N2 adsorption-desorption isotherms. Under optimized conditions, the viscosity of the heavy oil was decreased by 88.3%. The reaction temperature was reduced by about 70 °C compared with the traditional reaction. The results of the group composition analysis and the elemental content of the heavy oil indicate that the resin and asphaltene content decreases, and the saturated and aromatic HC content increases. The results of TGA and DSC of the heavy oil show that the macromolecular substances in the heavy oil were cracked into small molecules with low boiling points by the reaction. GC-MS examination of water-soluble polar compounds post-reaction indicates that B@Zn(II)L can diminish the quantity of polar substances in heavy oil and lower the aromatic nature of these compounds. Thiophene and quinoline were utilized as model compounds to investigate the reaction mechanism. GC-MS analysis revealed that C-C, C-N and C-S bonds were cleaved during the reaction, leading to a decrease in the viscosity of heavy oil.

Study on the Properties Changes of Reversible Invert Emulsion during the Process from O/W to W/O with Alkali

The reversible emulsion drilling fluid system combines the advantages of both oil-based and water-based drilling fluids, which can achieve ideal results in different stages of drilling and completion, and the system can be reused to effectively reduce costs. However, the research on reversible emulsions mainly focuses on the development of new reversible emulsifiers, while the specific phase transformation mechanism of reversible emulsion systems is still unclear. In this paper, a stable reversible emulsion was prepared using the reversible emulsifier DMOB as a raw material, and the reversible emulsion performance of the alkali response from the O/W emulsion phase to the W/O emulsion was studied. The microstructure of reversible emulsions was studied by a microscope, a cryogenic transmission electron microscopy, and a laser particle size analyzer. The changes in macroscopic properties of reversible emulsions in the process of alkali conversion were studied by pH, conductivity, demulsification voltage, static stability, viscosity, rheology, and other indicators, and the conversion mechanism of reversible emulsions from O/W emulsion ⟶ bicontinuous structure ⟶ O/W/O emulsion ⟶ W/O emulsion was clarified. The details are as follows: in the first stage, when the amount of NaOH ≤ 0.43 vol.%, the overall particle size of the emulsion decreases first and then increases with the increase in NaOH dosage. In the second stage, when the amount of NaOH was 0.45 vol.%, a double continuous structure was formed inside the emulsion. In the third stage, when the amount of NaOH is 0.48 vol.%, the O/W/O emulsion is formed, and with the increase in stirring time, the internal oil droplets gradually accumulate and are discharged from the water droplets, and finally, the W/O emulsion is formed. In the fourth stage, when the dosage of 0.50 vol.% ≤ NaOH ≤ 5.00 vol.%, the W/O emulsion was formed, and with the increase of NaOH dosage, the structure and compactness between water droplets increased first and then decreased. In the whole process, with the increase in the amount of NaOH solution, the total particle size of the emulsion first decreased and then increased.

The Phase Inversion Mechanism of the pH-Sensitive Reversible Invert Emulsion

Reversible emulsification drilling fluids can achieve conversion between oil-based drilling fluids and water-based drilling fluids at different stages of drilling and completion, combining the advantages of both to achieve the desired drilling and completion effects. The foundation of reversible emulsion drilling fluids lies in reversible emulsions, and the core of a reversible emulsion is the reversible emulsifier. In this study, we prepared a reversible emulsifier, DMOB(N,N-dimethyl-N'-oleic acid-1,4-butanediamine), and investigated the reversible phase inversion process of reversible emulsions, including the changes in the reversible emulsifier (HLB) and its distribution at the oil-water interface (zeta potential). From the perspective of the acid-alkali response mechanism of reversible emulsifiers, we explored the reversible phase inversion mechanism of reversible emulsions and reversible emulsification drilling fluids. It was revealed that the reversible phase inversion of emulsions could be achieved by adjusting the pH of the emulsion system. Then the proportion of ionic surfactants changed in the oil-water interface and subsequently raised/lowered the HLB value of the composite emulsifier at the oil-water interface, leading to reversible phase inversion of the emulsion. The introduction of organic clays into reversible emulsification drilling fluid can affect the reversible conversion performance of the drilling fluids at the oil-water interface. Thus, we also investigated the influence of organic clays on reversible emulsions. It was demonstrated that a dosage of organic clay of ≤2.50 g/100 mL could maintain the reversible phase inversion performance of reversible emulsions. By analyzing the microstructure of the emulsion and the complex oil-water interface, we revealed the mechanism of the influence of organic clay on the reversible emulsion. Organic clay distributed at the oil-water interface not only formed a complex emulsifier with surfactants, but also affected the microstructure of the emulsion, resulting in a difficult acid-induced phase transition, an easy alkali-induced phase transition, and improved overall stability.

Oil-Soluble Exogenous Catalysts and Reservoir Minerals Synergistically Catalyze the Aquathermolysis of Heavy Oil

Oil is the "blood" and economic lifeblood of modern industry, but traditional light crude oil has been over-consumed, and it has been difficult to meet human demand for energy, so the exploitation of heavy oil is particularly important. In this paper, an oil-soluble catalyst was synthesized to catalyze the pyrolysis reaction of heavy oil in collaboration with reservoir minerals, so as to achieve efficient viscosity reduction of heavy oil and reduce production costs. The experimental results showed that Zn(II)O + K had the best synergistic viscosity reduction effect after the aquathermolysis of No. 1 oil sample under the reaction conditions of 180 °C, 4 h, 30% of water, and 0.2% of catalyst, respectively, and the viscosity reduction rate was 61.74%. Under the catalysis of the isopropanol system, the viscosity reduction rate was increased to 91.22%. A series of characterizations such as freezing point, thermogravimetric analysis, DSC analysis, component analysis, gas chromatography, wax crystal morphology analysis, and GC-MS analysis of aqueous organic matter were carried out on heavy oil after reaction by different reaction systems, and it could be verified that the viscosity of heavy oil was reduced. Finally, through the study of the reaction mechanism of the model compound, combined with the aqueous phase analysis, it can be clearly found that the depolymerization between macromolecules, the breaking of heteroatom chains, hydrogenation, ring opening, and other effects mainly occur during the reaction, thereby weakening the van der Waals force and hydrogen bond of the recombinant interval, inhibiting the formation of grid structure in heavy oil and effectively reducing the viscosity of heavy oil.

Synthesis of Porous MgAl-LDH on a Micelle Template and Its Application for Efficient Treatment of Oilfield Wastewater

In this paper, a series of porous hierarchical Mg/Al layered double hydroxides (named as LDH, TTAC-MgAl-LDH, CTAC-MgAl-LDH, and OTAC-MgAl-LDH) was synthesized by a simple green hydrothermal method using wormlike micelles formed by salicylic acid and surfactants with different carbon chain lengths (0, 14, 16, and 18) as soft templates. BET, XRD, FTIR, TG, and SEM characterizations were carried out in order to investigate the structure and properties of the prepared materials. The results showed that the porous hierarchical CTAC-MgAl-LDH had a large specific surface area and multiple pore size distributions which could effectively increase the reaction area and allow better absorption capability. Benefiting from the unique architecture, CTAC-MgAl-LDH exhibited a large adsorption capacity for sulfonated lignite (231.70 mg/g) at 25 °C and a pH of 7, which outperformed the traditional LDH (86.05 mg/g), TTAC-MgAl-LDH (108.15 mg/g), and OTAC-MgAl-LDH (110.51 mg/g). The adsorption process of sulfonated lignite followed the pseudo-second-order kinetics model and conformed the Freundlich isotherm model with spontaneous heat absorption, which revealed that electrostatic adsorption and ion exchange were the main mechanisms of action for the adsorption. In addition, CTAC-MgAl-LDH showed a satisfactory long-time stability and its adsorption capacities were still as high as 198.64 mg/g after two adsorption cycles.