METHOD AND DEVICE FOR EXTRACTING COALBED METHANE BY DISCHARGING WATER AND COAL FINES

摘要

A method for extracting coalbed methane by discharging water and coal fines. A wellhead device (12) having a passageway delivers power fluid into an underground power fluid line (7) in a wellhole, then further conveys said fluid to a hydraulic jet pump (9) in a pump cylinder communicated with said underground power fluid line (7), enabling said pump (9) to operate. The pump (9) sucks in formation fluid via a suction inlet at the bottom of said pump, mixes said fluid with the power fluid to produce a mixed fluid and conveys same up to the ground surface. The mixed fluid, which contains coal fines, travels upward at a flow rate far greater than the settling rate of the coal fines, passes though the wellhead device and flows to the ground surface, thereby preventing the coal fines from settling back down. The suction inlet of the pump reaches the bottom boundary of the coal layer (8) so as to prevent coal fines from covering said layer, and the coalbed methane automatically shoots through the annular space of the well casing and up to a ground surface methane-collection device. A device for extracting coalbed methane by discharging water and coal fines is also disclosed. The method and device for extracting coalbed methane simplify the work of discharging coalbed water containing coal fines, thereby greatly reducing production costs and improving the overall effectiveness of coalbed methane extraction.