In the production process

part of the wells in southern Yanchuan CBM Field has the plugging characteristics of abnormal and rapid decline of gas production and liquid production. In order to analyze the causes of blockage

based on the changes of the production dynamic information of the liquid recovery

water quality and pump check of wells

the main cause of plugging is clarified

including scaling and pulverized coal. On the basis of analyzing the formation mechanism of scaling and pulverized coal blockage

the targeted prevention and treatment measures are carried out. For the scaling plugging wells

form a treatment measure comb

ining the normal prevention by adding scale inhibitor and the plugging removal by multi-stage pulse shock wave. 16 wells implemented by multi-stage pulse shock wave have got a good production increase with an average production increase of 30.11×10

4

m

3

per well. For the pulverized coal plugging wells

coal-carrying process by self-circulation and hollow rod well washing

and nitrogen foam well-unblocking treatment measures are formed. Well washing for carrying pulverized coal effectively alleviate the pump check caused by pulverized coal blocking pump

the gas well repair free period extended by 60 %. Four wells applied the nitrogen foam for unblocking achieve significant production increase

with an average daily production increase of 1.25×10

4

m

3

per well. The results provide references for the cause analysis and treatment of blocked CBM wells.