In order to solve the problem of frequent well laying in the coalbed methane field in south Yanchuan due to sand production（pulverized coal）

a novel drainage pump in south Yanchuan coalbed methane well has been developed. The novel drainage pump is designed as a forced pull rod hemisphere-type seal

and the plunger assembly adopts a hollow design. The pump diameter is

ø

38 mm

the stroke is three meters

the stroke time ranges from one to three times per minute

and the displacement is 4.8~14.6 m

3

/d. The novel drainage pump is used together with hollow rod and tubing

forming a dual-channel integrated pipe string for production an

d cleaning. It can not only meet the normal drainage gas production

but also facilitates well flushing and discharging pulverized coal. In addition

the flushing fluid does not enter the stratum during well flushing

avoiding the pollution of the flushing fluid to the stratum and preventing the failure of the fixed valve and the pump from being stuck caused by the deposition of pulverized coal or sand in the coalbed methane field drainage well. In 2022

the novel drainage pump was applied in two wells in the south Yanchuan coalbed methane field

and since then

no fixed valve failure or pulverized coal card pump has occurred. As a result the average pump inspection period of measure wells has been extended by 285 days. Field tests demonstrate that the novel drainage pump has the dual functions of normal gas drainage and coal powder discharge through well flushing

providing a new technical support for improving the overall development level of coalbed methane field in south Yanchuan.