Application Research of Circulating Water Injection Technology for Coal Powder Control in Zhengzhuang Block

Addressing the prevalent issues of coal dust blockage, frequent pump sticking, and severe equipment wear in coalbed methane wells in the Zhengzhuang block of the Qinshui Basin, a "portable + fixed dual-mode water injection system" collaborative operation and "one pump, three wells shunt joint injection" integrated technology are proposed based on the dynamic linkage mechanism of coal dust critical carrying velocity and the "injection-production balance" theory, to construct a closed-loop circulating water injection coal dust control system. By re-injecting high-pressure clean water into the tubing-casing annulus, the wellbore flow velocity and disturbance intensity are increased, achieving continuous suspension and carrying of coal dust and preventing coal dust deposition in the pump barrel and tubing string. The application in 11 coalbed methane wells on site shows that the coal dust average concentration at the wellhead has decreased from 6.5 g/L to 2.1 g/L, the average monthly frequency of pump sticking has decreased by 70%, the fluctuation range of extraction current has decreased from ±6.9 A to ±4.4 A, the average pump inspection cycle has been extended from 38 days to 115 days, with a maximum of 211 days, and the stable gas production rate has remained stable or even slightly increased. The system integrates variable frequency adaptive injection-production control and "one pump, three wells" shunt joint injection, supporting continuous powder carrying without production suspension, significantly improving equipment stability and operational efficiency.