Pressure control injection yield increase method for coalbed methane well

Abstract

The invention relates to a pressure control injection yield increase method for a coalbed methane well. The radius affected by the pressure of a created fracture after thehydraulic fracture according to the gas production rate, the coal seam thickness and the gas content per ton after the fracture of the coal petrography; the injection solution amount for yield increase is determined; a sleeve can be injected when the sand wash of the borehole operation is 10m far from a coal seam; two bottles of fracturing fluids are connected into an inlet of a plunger pump in parallel; the outlet of the plunger pump is connected with a sleeve valve of a gas collection tree, and a well mouth is provided with a pressure meter; and the accumulated water yield during the production period of a construction well is injected into the coal seam with the maximum pump discharge for filling the volume of the recover part, fluids can be injected by controlling the pressure, 5-20 Mpa injection amount of the fluids is injected in small pump discharge and steady pressure ways according to different pressures, the injection can be stopped when the stratum is saturated and the fluids can not be injected. The well mouth is pressure free in 3-5 days; and when the stratum is saturated and the pressure is not decreased to 5Mpa during the fifth-seventh day, the construction of the well can be finished. The invention has the beneficial effects that the method is suitable for the growth feature of the coal petrography of high order coal, the fracture conductivity is improved, and the generation of coal dust can be controlled.

Description

technical field [0001] The invention relates to a novel production-increasing process method in the production-increasing operation of high-rank coal coal bed methane. Background technique [0002] For vertical well development of coalbed methane, fracturing is one of the main measures to increase production. At present, the hydraulic fracturing process is commonly used for vertical well fracturing, and the construction parameters: injection fluid volume is 400-600m 3 , injection pressure 8~22MPa, sand volume 30~50m 3 , Displacement 4~9m 3 / min, 2 hours after the pressurization, flow back gas production. According to statistics, after fracturing of coalbed methane wells in the Qinshui area, 1 / 3 of the gas production failed to meet the requirements of the development plan. According to laboratory experiments combined with on-site fracturing construction curves, it is proved that the structure of high-rank coal is quite different, and there is a large plastic deformation. ...

AI Technical Summary

Problems solved by technology

Overcome the deficiencies of existing fracturing methods that easily cause damage to coal and rock such as fragmentation, collapse, and accumulation of fly ash

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