Broken soft thin coal seam gas extraction directional long drilling construction drilling tool assembly and method

Abstract

The invention discloses a broken soft thin coal seam gas extraction directional long drill hole construction drilling tool assembly and method. The broken soft thin coal seam gas extraction directional long drill hole construction drilling tool assembly comprises a directional drill bit, a front measuring short section, a non-magnetic wire passing screw drill tool, a rear measuring short section and a central cable passing drill rod which are connected in sequence. The front measuring short section is used for measuring a drill hole inclination angle, a tool face angle and stratum natural gamma radioactive intensity at a near-bit position; the non-magnetic wire-passing screw drilling tool is used for providing rock crushing power for the directional drill bit and transmitting measurement data of the front measurement short section to the rear measurement short section through the non-magnetic wire-passing screw drilling tool side wall communication assembly; the rear measurement short section is used for receiving measurement data of the front measurement short section and measuring a drilling azimuth angle; and the central through cable drill rod is used for uploading hole bottom measurement data. According to the technical scheme, the hole forming depth and the hole forming rate of the broken soft thin coal seam gas extraction drill hole can be effectively improved, the gas treatment period is shortened, and the gas treatment cost is reduced.

Description

technical field [0001] The invention belongs to the field of underground gas drainage in coal mines, and in particular relates to a directional long drilling construction drilling tool assembly and a method for gas drainage in broken soft thin coal seams. Background technique [0002] Thin coal seams are widely distributed in my country, mainly referring to coal seams with a thickness less than 1.3m, accounting for about 20% of my country's coal resource reserves. In order to improve the recovery rate of coal, my country stipulates that coal seams with a thickness greater than 0.8m must be mined, and coal seams with a thickness less than 0.8m are encouraged to be mined. However, gas control in broken, soft and thin coal seams has become a major problem restricting its safe and efficient mining, because of the shallow hole depth and low hole formation rate of gas drainage in broken, soft and thin coal seams. [0003] Due to the small thickness of the soft and thin coal seam ...

AI Technical Summary

Problems solved by technology

However, gas control in broken soft and thin coal seams has become a major problem restricting its safe and efficient mining, because the drilling depth of gas drainage in broken and soft thin coal seams is shallow and the porosity rate is low

[0003] Due to the small thickness of the soft and thin coal seam and large fluctuations, the drilling trajectory of the conventional rotary drilling technology is uncontrollable, and it is easy to touch the top or bottom, resulting in fewer effective gas extraction holes. The inclination angle, azimuth angle, tool face and other parameters of the borehole are used to guide the adjustment of the borehole trajectory, and it is difficult to accurately judge the formation lithology and coal-rock interface by relying solely on the change of the borehole return water to judge the formation situation. knowledge

Secondly, the measurement-while-drilling probe is arranged about 6m away from the drill bit, and there is a lag in the control of the drilling trajectory. The drill bit is easy to drill out of the thin coal seam, which makes it difficult to open branch holes, and it is difficult to ensure the precise extension of the drilling trajectory along the thin coal seam.

In addition, the downhole directional drilling technology uses clean water as the flushing fluid, which greatly disturbs the pore wall of the broken soft and thin coal seam, resulting in frequent hole collapse and injection hole accidents, and is difficult to adapt to the long-distance pore forming of the broken soft and thin coal seam.

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