Reverse circulation drilling device and process for soft projecting coal seam

Abstract

The invention provides a reverse circulation drilling device for a soft projecting coal seam. The device comprises a drilling machine, an active double-wall drilling rod, a double-channel pneumatic faucet; a power head is arranged on the drilling machine; the active double-wall drilling rod passes through the power head to be mounted; an inner pipe at one end of the active double-wall drilling rod is connected with a rubber pipe through the double-channel pneumatic faucet; a pulverized coal receiving device is connected to the tail end of the rubber pipe; an air box which communicates with internal and external pipe annular channels of the active double-wall drilling rod is arranged on the double-channel pneumatic faucet; the air box is connected with an air compressor through an air pipe; a drill bit is connected to the other end of the active double-wall drilling rod. With the adoption of the device, the disturbance to the coal seam can be minimized, so that the collapse in holes can be effectively prevented, and that the frequent drilling blocking accidents can be avoided; the circumstance that gas is concentrated is prevented, and therefore, the phenomenon of blowout through the holes can be effectively avoided; the production cost is low; in addition, the working environment at the construction field can be effectively improved; the purpose of drilling in collapse and reducing stratums synchronously by one drilling rod can be achieved.

Description

technical field [0001] The invention relates to the technical field of geological drilling, in particular to a reverse circulation drilling equipment and drilling technology for soft and outburst coal seams. Background technique [0002] Soft and outburst coal seams account for a large proportion of mineable coal seams in my country. Drilling in soft outburst coal seams, especially in areas with high ground stress, is prone to phenomena such as jet holes, hole collapse, and drill sticking, resulting in low hole forming rate, shallow hole forming depth, and difficult drilling construction. At present, the most advanced technology for soft and outburst coal seams is the mid-wind pressure air drilling technology developed by the Xi'an Research Institute of the Coal Research Institute. [0003] The medium wind pressure air drilling technology uses an independent drilling air supply system to supply medium wind pressure (1~1.3MPa) and large displacement (17m 3 / min) of compress...

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Problems solved by technology

[0004] 1. An air compressor with medium wind pressure and large air volume needs to be configured, which consumes a lot of power, takes up a lot of space for the equipment, and has high construction costs;

[0005] 2. Two types of drill pipes are used for the collapsed formation and the reduced diameter formation, which is costly and difficult to deal with both collapsed and reduced diameter formations;

[0007] 4. The hole wall gap is blocked due to hole collapse and diameter reduction. Even if the auger drill pipe is used, it is impossible to dredge the upward and return passage immediately. Once a large amount of gas in the coal seam is released, it will accumulate at the blockage. When the gas release volume and release pressure When it reaches a certain level, the nozzle hole phenomenon will be inevitable;

[0008] 5. Due to positive circulation drilling, pulverized coal is discharged from the orifice, which is difficult to collect and process, and cannot effectively improve the on-site operating environment

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