Research on fluorocarbon cleaning agent and action mechanism of oil-based drilling cuttings in shale gas well

Oil-based drilling cuttings will be produced during the drilling process of shale gas development. Thermochemical cleaning is one of the main technologies to treat oil-based drilling cuttings. However, there are shortcomings in the application process, such as low oil removal efficiency of existing oil removal agents and lack of theoretical guidance for the development of new drugs. Using contact angle measuring instrument, X-ray diffractometer and other analytical methods, the adsorption mechanism of oil on the surface of oil-based drilling cuttings was studied, and a new “hydrophobic and oleophobic” fluorocarbon oil cleaning agent was synthesized, and the molecular structure of the synthesized product was analyzed. Infrared spectroscopy and nuclear magnetic resonance spectroscopy and other analytical characterization. The research results show that different oils have different effects on the wettability of oil-based drilling cuttings. Diesel oil is easier to spread on the surface of oil-based cuttings with low clay mineral content. Different oils have a large adsorption capacity 0.1-0.2 g/g on the surface of clean drill cuttings, and the adsorption equilibrium can be reached within 2-3 hours. The adsorbed organics were mainly C₁₆-C₂₀ normal and isoparaffins, accounting for 56.5% of the total organics. After oil-based drilling cuttings are washed with "hydrophobic and oleophobic" fluorocarbon oil washing agent, the oil content is reduced from 7%~10% before treatment to 0.15%-0.97%. And it is lower than the SDS 2.08%-2.79% of the oil-bearing drilling cuttings degreaser on site. And the mechanism of "hydrophobic and oleophobic" degreaser changing the oil phase contact angle, reducing the oil-water interfacial tension of oil-based drilling cuttings and changing its wettability is studied, which can provide information for the development and application of oil cleaning agent for oil-based drilling cuttings.