Preparation and verification of chemical plugging slurry for CBM boreholes

In order to solve the problem of leakage of coalbed methane wells in a mining area in Shanxi, through choosing suitable plugging slurry, using PHP, 801 plugging agent, water glass and vegetable gum as plugging materials, the index of plugging slurry was measured including specific gravity, water loss, plastic viscosity, apparent viscosity, and dynamic shear force. The significance of each material(factor)was analyzed by range analysis and variance analysis. The results showed that the plastic viscosity and apparent viscosity were most affected by PHP; water glass had the greatest impact on the water loss time; the 801 plugging agent had the greatest impact on the dynamic shear force. The optimum formulation of plugging slurry was determined with larger viscosity, larger shear force and lower water loss. The rheological equation of the optimal formula for plugging slurry was established. The plugging performance of the plugging slurry was measured by simulation test. The plugging efficiency of plugging slurry was inspected by four CBM drilling engineering practices.