Ultralow surface tension foam scrubbing agent and preparation method thereof

The invention discloses an ultra-low surface tension foam scrubbing agent and a preparation method thereof. The foam scrubbing agent with the ultralow surface tension is prepared from the following components in parts by mass: 20 to 40 parts of gemini dodecyl dimethyl hydroxypropyl sulfobetaine, 0.1 to 1 part of perfluorononenoxy sodium benzenesulfonate, 1 to 4 parts of coconut oil fatty acid monoethanolamide and 59 to 79 parts of water. The gemini dodecyl dimethyl hydroxypropyl sulphobetaine is a gemini surfactant which is obtained by substituting a hydroxyl group in dodecyl dimethyl hydroxypropyl sulphobetaine through 1, 4-dibromobutane. The foam scrubbing agent with the ultralow surface tension can further improve the oil and gas recovery rate of an ultralow-yield well, solves the problems of water logging, yield reduction and the like when the gas well productivity is extremely low in the later period of gas well exploitation, and meets the foam scrubbing process requirements of the ultralow-yield well (b