Green Surfactant Made from Cashew Phenol for Enhanced Oil Recovery.

Surfactants play an important role in enhancing oil recovery (EOR). With the development of tertiary oil recovery technology and the continuous improvement of environmental protection requirements, green environmentally friendly surfactants play an important role in replacing conventional surfactants. In this paper, cardanol polyoxyethylene ether (CPE) was synthesized from natural biomass cardanol. Its structure was characterized, and its surface/interface properties, salt and temperature resistance, wettability, emulsification, and oil displacement effect were studied experimentally. The results showed that CPE had good interfacial activity and temperature and salt tolerance, which can reduce the oil-water interfacial tension to 10-1 mN/m. The emulsion formed by CPE had good stability. With the increase in CPE dosage, the droplet size of the emulsion decreases. The emulsion stabilized by CPE can effectively enhance oil recovery by 11.8%. Therefore, CPE not only is environmentally friendly but also has great application potential in the field of EOR.

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.

Resource utilization of medical waste under COVID-19: Waste mask used as crude oil fluidity improver.

The disposal of medical waste has become an increasing environmental issue since the COVID-19 epidemic outbreaks. Conventional disposal methods have produced waste of fossil resources and environmental problems. In this study, the waste medical mask-derived materials were tested as viscosity reducer and pour point depressant to evaluate the possibility of being used as crude oil fluidity improver. The results show that the materials derived from the three parts of the waste medical mask can reduce the viscosity and pour point of each crude oil samples from different oilfields in China. The middle layer of the medical mask (PP-2) displays the highest efficiency, and the viscosity reduction rate and maximum pour point reduction reaches 81% and 8.3 °C at 500 ppm, respectively. A probable mechanism of improving rheological properties of the crude oil samples by the medical mask-derived materials was further proposed after the differential scanning calorimetry (DSC) analysis and the wax crystal morphology analysis. We hope this work could provide a way to solve the current environmental issues under COVID-19.

The Effect of the Hydrate Antiagglomerant on Hydrate Crystallization at the Oil-Water Interface.

Clathrate hydrates are ice-like compounds consisting of small gas molecules enclosed in water molecule cages. The formation of gas hydrate in oil and gas pipelines may result in flow assurance failure and serious safety and environmental concerns. Antiagglomeration is a promising method to mitigate gas hydrate risks in hydrocarbon flowlines. Morphological behavior of hydrates in the presence of antiagglomerants can provide important information on the antiagglomeration mechanisms. This study reports the visual observations of the morphology of hydrate formed with a water droplet immersed in cyclopentane with and without the presence of a hydrate antiagglomerant (AA). The effect of AA on the hydrate crystal growth was investigated. The AA exhibited a kinetic inhibition effect. With no AA, a faceted hydrate shell formed around the water droplet was observed. The subcooling can affect the rate of lateral growth. Higher subcooling facilitates hydrate growth. With the presence of 0.04 wt % AA, a hairy and porous morphology of hydrate was observed. At higher AA concentrations, a vertical type of growth after the lateral growth of the hydrate shell was observed. This is probably the first report of vertical growth of cyclopentane hydrate formed with a water droplet. A hypothesis is proposed to explain the vertical growth mechanism of the hydrate crystals.