Study and application of gas surface well broken protection in mining area

In order to overcome the technical problem of the well body easy breakdown in the gas drainage of the gas surface well in the mining area, a technical conception with “avoiding”,“yielding”,“prevention”and “drainage”was applied to optimize and improve the gas drainage technology of the surface well in the mining area. With the application of the “avoiding” theory, the layout law of the surface wells in the mining area was obtained. With the application of the “yielding” theory, a local cementing technology was improved, local cementing method was provided and a horizontal displacement value was “yielded”. With the application of the “prevention” conception, the local protection device, deflection structure, telescopic structure and thick wall rigid structure were developed. With the application of the “drainage” conception, the suspension well completion technology was researched and developed and the sand jammed problem at the three open screen pipe section was solved. An engineering application was conducted in Yuecheng Mine of Jincheng Anthracite Coal Mining Group, No. YCCD-02 well was continuously drained with 35 months and the total drained gas volume was about 13 million m3. After the gas drainage operation of the surface well, the gas volume fraction in the air returning gateway of the coal mining face was reduced by 58.75% and the gas volume fraction in the upper corner was reduced by 56%.The technology protected the safety mining of the mine,and would have promotion value.