Objective In order to meet the needs of stable production of foam drainage and control of bacterial corrosion in shale gas wells, a compound bactericidal foaming agent with functions of foam drainage, bactericidal and antiseptic at 150 ℃ well temperature was developed.

Methods Combined with the analysis of foam formation to burst process, through the optimization of foaming agent, foam stabilizing agent and bactericidal agent, compound bactericidal foaming agent was formed and verified by field test.

Results At 90 ℃ and the mass concentration of 1.0 g/L, the initial bubble height was more than 185 mm, the 5 min bubble height was more than 122 mm, and the liquid carrying capacity was greater than 149 mL/15 min. At 5 MPa, 150 ℃ and the mass concentration of 2.0 g/L, the foaming volume was more than 650 mL, and the foam volume decreases less than 10% at 1 000 s. The bactericidal rate of sulfate reducing bacteria(SRB) was 100% at the the mass concentration of 1.0 g/L. In the field application test, the gas yield and water yields of conventional foamer and compound bactericidal foamer with the same the mass concentration were equal, the gas yield and water yield of the wells without foam drainage were stable after using the compound bactericidal foaming agent, and the bactericidal rate was over 98.0%.

Conclusions The compound bactericidal foaming agent has functions of foam drainage, bactericidal and antiseptic. It can be used for stable production and bactericidal antiseptic of foam drainage in 150 ℃ shale gas well.