Synthetic expanded polytetrafluoroethylene (ePTFE) membrane has a wide range of applications, including aerosol and dust removal, and exhibits high dust-removing efficiency, high air permeability, and cost-effectiveness. However, the intrinsic oleophilic surface of ePTFE limits its application in the oil-bearing gas–solid separation process. Herein, we report a surface modification method to prepare amphiphobic ePTFE membranes via coating of a layer of 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (PFTMS) – modified nano-SiO2 onto the surface of ePTFE fibers. The oil contact angle of the modified ePTFE membranes was increased from 0 to 123°, while retaining the initial water contact angle of 142°. The amphiphobic membrane shows excellent oil aerosol filtration efficiency with a comparative low pressure drop and high oil rejection rate of 99.5%. Remarkably, the membrane can be reused after simple rinsing with water. The oil aerosol filtration efficiency of membrane remained as high as 98.5% after five cycles of filtration and cleaning.
Drilling fluid additives that maintain wellbore stability have attracted considerable attention because of the frequent occurrence of wellbore instability accidents during drilling operations. However, achieving long-term wellbore stability in practical applications remains challenging. Herein, we report the application of chitin-based amphiphobic nanocomposites (PFTMS@ChNCs/SiO2) to maintain the wellbore stability of oil-based drilling fluids (ODFs). The PFTMS@ChNCs/SiO2 was prepared using a template approach, generating silica shells on the surface of chitin nanocrystals via the sol–gel method, followed by modification with 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (PFTMS). The PFTMS@ChNCs/SiO2 exhibited excellent thermal and chemical stability; even after heating in hot air at 200 °C for 24 h or soaking in hot fluids at 150 °C for 7 d, the contact angle of water and oil on the PFTMS@ChNCs/SiO2 remained above 120°, making them suitable for the harsh drilling fluid conditions. The shale treated with PFTMS@ChNCs/SiO2 demonstrated remarkable liquid-repelling properties and maintained good mechanical strength even after prolonged immersion in high-temperature fluids. Moreover, incorporating PFTMS@ChNCs/SiO2 into ODFs improved their performance, including enhanced rheological properties, better filtration control, and improved mud cake quality. Filtration tests showed a 39.6% reduction in fluid loss, whereas the filtration medium permeability decreased to 0.211 × 10–4 mD. This study presents a promising method for wellbore stabilization in ODFs and a direction for chitin nanocrystals in oil and gas engineering applications.
危险品化学品经营许可证（带存储）