1. Introduction
To undertake the project of directional drilling for high-level gas drainage from roof in 3109 working face of Duanshi Coal Mine of Qinhe Energy Group Co. , Ltd. , the final hole trace is located in the middle and lower part of No. 3 coal roof fracture zone to extract gas from upper corner of working face and goaf. Before the borehole enters the target horizon, it has to pass through two layers of broken coal line and several layers of weak alternating strata.
2. Solution
According to the variation of drilling parameters and drilling cutting, the lithology of the formation is comprehensively judged. Thickness and height of the complex formation are accurately located by increasing the inclination of the drilling hole in the climbing section. Shortening the length of footage and enlarging the diameter in the complex formation help the boreholes passing through the complex fractured formation successfully. By means of the technique of sidetrack drilling, mudstone formation was bypassed, and the boreholes met the design requirement.
3. Construction situation
7 high position directional drilling boreholes were accomplished In the 3109 working face of Duanshi Coal Mine. Maximum borehole depth is 552m, and borehole diameter is 153mm. Cumulative construction footage is 3488m. while the final borehole layer is between 30 ~ 45m in the roof of No.3 Coal Seam.
4. Achieved accomplishment
During mining process of 3109 working face, the average gas drainage pure flow rate reached 11.55 m3/min and the average single-hole drainage concentration reached 34.68% , which effectively reduced the gas concentration in the working face and ensured mining safety.
Hot Tags: directional roof drilling, China, manufacturers, suppliers, factory, wholesale, price list, buy, for sale,
