Influencing characteristics and control of coal powder to proppant fracture conductivity

In order to deal with the problem of coal powder damage in the process of CBM(coalbed methane),the well changing flow velocity,constant flow velocity and discontinuous flow production,the coal powder migration and deposi- tion in proppant fracture were simulated with LD-1A proppant conductivity testing system. Influencing characteristics and damage mechanism of coal powder to proppant fracture conductivity under different flow velocities were analyzed. Experimental results show that coal powder easily deposits in the bottom of the proppant fracture and seriously damage the fracture conductivity. The damage rate of fracture conductivity is up to more than 90% . Fracture conductivity has an increasing tendency when coal powder discharge effectively in the condition that coal powder isn’t added to prop- pant fracture continuously. Influencing characteristics of production system,coal powder content and diameter to flow conductivity have obvious differences. Coal powder plug and dredge in proppant narrow pore influence the proppant fracture conductivity together when migration with water. Proppant in smaller diameters was employed at the beginning of fracturing,then proppant in bigger diameters was used. Flow velocity is controlled reasonably to ensure that the flow velocity is less than coal powder migration critical velocity. And coal powder dispersion agent is employed for fractu- ring. They are good for coal powder discharging effectively and reducing the fracture conductivity damage.