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

Four products were obtained from sodium dodecylbenzene sulfonate (SDBS) and formaldehyde (40% solution) using a simple reaction. The products were characterized by TGA, IR, UV and MS to confirm the major chemicals in each sample. The new products could reduce the interfacial tension between oil and water in the experimental temperature range further compared to SDBS. The emulsion ability was also enhanced by SDBS-1 to SDBS-4. The oil-displacement efficiencies of SDBS-1 to SDBS-4 were obviously higher than that of SDBS, and the oil-displacement efficiency of SDBS-2 was the best, with an efficiency of 25%. The experimental results all indicate that these products have an excellent ability to reduce oil-water interfacial tension and that they can be used in the oil and petrochemical industry for oil production and have certain practical uses.

Use of Betaine-Based Gel and Its Potential Application in Enhanced Oil Recovery

In this paper, a betaine-based gel containing 2.0% erucamide propyl betaine (EAPB), 0.5% oleic acid amide propyl betaine (OAPB), and 0.1% KCl was prepared for use as a fracturing fluid. The performance evaluation showed that KCl may improve the temperature resistance and increase the viscosity of the optimized fracturing fluid. At 80 °C, the apparent viscosity of the viscoelastic surfactant (VES)-based fracturing fluid was approximately 50 mPa·s. Furthermore, the gel had high shear resistance, good viscosity stability, and high sand-carrying performance. After being sheared at 170 s−1 for 60 min, the reduction in viscosity was 13.6%. The viscosity of the gel was relatively stable at room temperature (27 °C) for one week. In a suspension containing 10% sand (particle size < 0.45 mm, density = 2.75 g cm−3), the settling velocity of proppant particles was 1.15 cm h−1. In addition, we detected that the critical micelle concentration of this gel was approximately 0.042 wt%. The viscosity could be reduced to <5 mPa·s at 60 °C within 1 h when 6.0% crude oil was present, and oil displacement experiments showed that the broken fracturing fluid can enhance the oil displacement rate up to 14.5%. This work may facilitate research on fracturing fluids and oil recovery.