Reverse circulation aerodynamic cavitation method for coalbed methane well and equipment

Abstract

The invention discloses a reverse circulation aerodynamic cavitation method for a coalbed methane well and equipment. The reverse circulation aerodynamic cavitation method comprises the following steps of: arranging wellhead equipment on a wellhead and sinking a working pipe to a bottom hole; clearly eliminating rock coal dust and water inside the well by using an air compressor in a circulating way; then lifting the working pipe upwards and injecting air / foam by using the air compressor and a supercharger, wherein the air injecting pressure is 3-15 MPa; meanwhile continuously injecting atomized water into the well with the water injecting amount of 3.0-5.0 m<3> each time; opening a hydraulic flat plate gate valve for discharging; after discharging, sinking the working pipe to a coalbed part; injecting the air simultaneously by the air compressor and the supercharger; meanwhile injecting water / foam with the amount of 3.0-10.0 m<3> by using an injection pump for washing the well to thebottom hole; after completing one cycle of discharging and well washing, detecting initial data; closing the air compressor, the supercharger, the injection pump and the hydraulic flat plate gate valve to enable gas inside the well to return freely; measuring the change of gas output of coalbed gas in one hour by using a flow meter; and placing a torch at a discharge port to ignite the gas. The invention improves the construction safety, improves the yield of single well coalbed gas, and saves the construction cost.

Description

technical field [0001] The invention belongs to the technical field of coal bed gas well completion, and mainly relates to a reverse circulation aerodynamic cavitation method and equipment for coal bed gas wells. Background technique [0002] Among the proven coal reserves, low-rank coal, fragmented coal and soft coal seams account for a considerable proportion, and the abundant coalbed methane (mainly composed of gas) contained in coal seams is not only the main safety hazard of coal mining, but also a A new type of clean energy. The currently used perforation and fracturing drainage technologies for low-rank coal seams cannot achieve the purpose of drainage because of their low closure strength, and the cracks formed by fracturing are easy to reclose. For fragmented coal, the cracks mainly develop along the weak structural plane in the coal seam. Because of the presence of fine coal powder in the structural plane, it is easy to block the cracks formed by fracturing, so it...

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Problems solved by technology

The currently used perforation and fracturing drainage technologies for low-rank coal seams cannot achieve the purpose of drainage due to the low closure strength and the cracks formed by fracturing are easy to reclose.

For fragmented coal, the cracks mainly develop along the weak structural plane in the coal seam. Because of the presence of fine coal powder in the structural plane, it is easy to block the cracks formed by fracturing, so it is difficult to achieve the purpose of drainage; mechanical cave completion drainage Due to the small caves formed, the exposed coal seam surface area is small, and the coal seam permeability is low, the purpose of drainage and mining of low-rank coal and fragmented coal cannot be realized; the risk of constructing horizontal branch wells in low-rank coal and fragmented coal seams Extremely large, mainly because the coal seam is soft and broken, and it is easy to collapse and cause drilling accidents, so it is impossible to realize the exploitation of coalbed methane in low-rank coal seams and fragmented coal seams

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