关键词: 穿越采空区, 岩层扰动带, 井身结构, 钻进方式, 瓦斯

Abstract: For the construction of surface gas vertical wells for gas pre-extraction in deep coal seams, during the drilling process, it is necessary to drill through the goaf of the upper coal seam. However, it is difficult to return rock cuttings due to drilling fluid leakage for the section passing through the goaf. In order to drill through the goaf quickly and safely, it is based on the calculation formulas for the height of the collapse zone, fracture zone, and bottom plate water conduction failure zone in the "upper three zones", the depth of the well section prone to drilling fluid leakage is obtained. The optimized structure of the fourth spud well and the corresponding circulating medium used in the well section are proposed. On this basis, combined with the geological conditions of the SiHe mining area in the Qinshui Basin, the well structure design and circulating medium performance design were carried out, and a vertical well for gas extraction through the goaf was successfully implemented. The results show that for the first, second, and fourth spud sections drilling by using water-based drilling fluid systems with minimal leakage, while the third spud section is drilled by using nitrogen circulation medium, which have achieved efficient and smooth passage through the goaf at once, achieving the goal of rapid and safe completion.

Key words: through goaf, rock disturbance zone, well structure, drilling method, gas