近年来,随着西气东输一线、二线的建设,水平定向钻穿越管径已达到1 219 mm,使后续的扩孔孔径增至1 600 mm以上,进而使扩孔级数增加,极易产生孔洞剖面形状不规则,导致坍塌、卡钻、甚至穿越失败。为此,分析了成孔质量的影响因素,包括穿越地层性质、扩孔级差、扩孔直径、泥浆性能、钻具组合、钻具泥浆喷嘴布置,机械操作技术等。提出采用轻量化钻具、调整喷嘴的喷射方向、在钻具直径变化较大处增加导向器、优化钻具组合等方法提高水平定向钻孔洞剖面成孔质量。该方法在西二线渭河穿越施工中成功应用,孔洞质量控制水平得到明显提升,提高了水平定向钻在中粗砂等低承载力地层的穿越能力,降低了施工风险。(图4,表2,参7) In recent years, with the construction of the first and second lines of the West-East Gas Pipeline, the diameter of horizontal directional drilling has reached 1 219 mm, increasing the subsequent reaming aperture to over 1 600 mm, thereby increasing the number of reaming steps. Resulting in irregular shape of the hole cross-section, leading to collapse, stuck, and even failed to cross. For this reason, the influencing factors of pore formation quality were analyzed, including the nature of the crossing strata, the degree of reaming, the diameter of reaming, the performance of mud, the combination of drilling tools, the arrangement of drilling mud nozzles and the mechanical operation technique. Propose the use of lightweight drilling tools to adjust the jet direction of injection nozzle in the larger changes in the diameter of the drill guide to optimize the combination of drilling and other methods to improve the quality of horizontal directional drilling hole profile. The method has been successfully applied in the construction of the Weihe River crossing the Second West Weihe River. The quality control of the holes has been obviously improved, which improves the crossing ability of horizontal directional drilling in low-bearing strata such as medium coarse sand and reduces the construction risk. (Figure 4, Table 2, reference 7)