Study on Leakage Plugging Technology of CBM Drilling Under Complex Geological Conditions

In view of the leakage problems encountered in the drilling process in the study area, a plugging technique for different leakage sizes and leakage velocity is developed based on the analysis of geological conditions. The leakage type mainly includes the pressure induced leakage and fracture loss of sand shale, and we propose the corresponding measures that the compound plugging agent, one-way closure and sawdust are added in the sand-mudstone of seepage and longitudinal fissure; when the leakage is large, using the larger particles of bentonite soil, cotton seed shell can appropriately increase the viscosity of drilling fluid for plugging.