The national invention patents applied by Southwest Oil and gas field, "A CYT-1 concentric dredge gas lift tool and usage method" and "gas well foam drainage laboratory simulation test device", have recently been authorized by the State Intellectual Property Office.Concentric dredging gas lift tool can realize no workover and check valve operation, save operation cost millions of yuan for single well, and provide a practical, economical and effective technical means for water and gas well to implement drainage gas recovery process.Through the successful application of more than 10 Wells on site and continuous optimization and improvement of tool performance parameters, 4 series of gas-lift drainage gas recovery tools and corresponding construction and maintenance technologies have been formed in 2 types of concentric and hierarchical concentric dredging gas recovery tools.