The invention provides a drainage device for a
coal bed gas well electric submersible
centrifugal pump, which is applied to the technical field of
coal bed gas mining. The device is characterized in that a
pressure sensor and a well head flow
governor are fixed on an outlet line of liquid; the lower end of an oil
pipe is connected with the outlet end of the electric submersible
centrifugal pump; and the inlet end of the electric submersible
centrifugal pump is connected with a motor of a drainage pump and a gas-liquid separator. The invention has the effects that (1) drainage function with large pump lift and low delivery capacity can be realized through
intelligent control; (2) the gas-liquid separator can prevent
soot from entering the electric submersible centrifugal pump, and can effectively realize that the
coal bed gas is separated from water, thereby ensuring efficiency and stability of centrifugal pump operation; (3) an underground liquid level indicator can monitor height of an underground liquid surface in real time, thereby monitoring the effect of coal bed gas technology realization on one hand, and ensuring safe and stable operation at a high speed of the electric submersible centrifugal pump on the other hand; (4) under comprehensive effects of a controller, the flow
governor, the underground liquid level indicator and the electric submersible centrifugal pump, technology of 'fixed-flow drainage' and 'fixed-liquid level drainage' needed in the process of coal bed gas exploitation can be realized.