Construction method for high-level large-diameter directional drilling of complex roof

Abstract

The invention discloses a construction method for high-level large-diameter directional drilling of a complex roof. The construction method comprises the steps that a hole is drilled from a positive angle in a coal seam, and a guide directional hole of a casing hole section is drilled to penetrate through a roof and a weak broken layer to reach a stable extraction layer; then counterboring is performed along the guide directional hole of the casing hole section to the bottom of the hole; a protective casing is lowered from a hole opening to protect a hole section of the weak broken layer; holesealing materials are injected into the annulus of the protective casing and the drill hole wall to seal the protective casing; a measurement-while-drilling directional drilling tool assembly penetrates through the casing hole section, and drills a guide directional hole of a main extraction hole section to the design hole depth along a design trajectory; and the measurement-while-drilling directional drilling tool assembly is removed, and counterboring is carried out on the basis of the guide directional hole of the main extraction hole section, and hole drilling is finished in the form of open holes. Therefore, the difficulty in hole drilling and forming and interruption of borehole gas extraction due to the collapse of the hole wall of the weak broken layer during the construction of the main extraction hole section and in the later extraction process are avoided, the large-diameter counterboring is further implemented on the main extraction hole section by penetrating through thecasing hole section, and the gas extraction effect is improved.

Description

technical field [0001] The invention relates to the technical field of coal mine tunnel drilling, in particular to a construction method for high-position and large-diameter directional drilling on complex roofs. Background technique [0002] Borehole drainage is an important way to control coal mine gas in my country at the present stage. Directional drilling with high position and large diameter on the roof is an important means to relieve the pressure of gas in the area affected by mining in the mining face. , It is of great significance to realize gas resource extraction and utilization. [0003] Roof high-level directional drilling is a group of strike-oriented long drilling holes constructed from the high-level directional drilling site opened along the backflow trough of the working face or adjacent to the roadway to the roof of the coal seam. High-concentration gas achieves the purpose of gas control in the working face. The structure of high-level directional drill...

AI Technical Summary

Problems solved by technology

However, on the basis of the existing roof high-position directional drilling structure, the traditional casing running process has the following disadvantages: first, the inner diameter of the running casing must be larger than the diameter of the final hole of the drilling hole, and the reaming diameter of the casing hole section must also be larger than the casing Outer diameter, taking the high-position large-diameter directional drilling of Φ153mm roof as an example, the specification of the lowered steel casing is generally Φ178mm, and the reaming diameter of the casing hole section should not be less than Φ193mm. If the diameter of the final hole increases, the casing specification Corresponding to the increase of the reaming diameter, this will not only increase the workload of reaming, but also increase the stiffness and weight of the casing, increasing the difficulty of running the casing; secondly, in order to obtain the ideal hole wall stabilization effect , the lowering depth of the casing should theoretically pass through the weak fractured layer, and the deepest may cover the entire climbing hole section. Due to the overall curvature of the drilling track in this hole section, the difficulty of running large-diameter casings is further increased, and even cannot be lowered to the predetermined position. , leading to casing failure

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