Solid foam drainage agent applied to gas field

The invention relates to a solid foam drainage agent, which is composed of the following raw materials in percentage by mass: 40-50% of surfactant, 5-20% of sodium carbonate and 40-55% of sodium dihydrogen phosphate. The solid foam drainage agent disclosed by the invention is strong in foaming capacity, rich in foam, high in foam moisture content and high liquid load, and is excellent in salt, methanol and oil resistance; the solid foam drainage agent shows good compatibility with underground auxiliaries and is quite stable in product performance; foam drainage success rate in a field test is quite high; and the solid foam drainage agent is applicable to shaft drainage in natural gas extraction, and in particular to gas wells of high temperature (100 DEG C), highly condensate oil (less than or equal to 50%), methanol resistance (less than or equal to 30%) and high salinity (less than or equal to 200000mg/L).