Foam scrubbing agent used for water drainage and gas collection of water-production gas well containing H2S gas

The present invention provides a foam scrubbing agent used for water drainage and gas collection of a water-production gas well containing H2S gas. The foam scrubbing agent included the following raw materials: 10-30% of an anionic-nonionic surfactant, 20-40% of a zwitterionic surfactant, 5-15% of an anionic surfactant and balance of deionized water. The present invention also provides a preparation method of the foam scrubbing agent, and the preparation method is as follows: the anionic-nonionic surfactant and the zwitterionic surfactant are added into a stainless steel reaction kettle in one time, and the deionized water is added to obtain a liquid mixture, the liquid mixture is heated to 40-50 DE GC, and stirred, the anionic surfactant is slowly added into the liquid mixture, and stirred to obtain the foam scrubbing agent. The foam scrubbing agent can good foaming characteristic and foam stabilization characteristic in formation water dissolved with the H2S gas.