煤层气水平井生产面临完井管柱沉砂堆积、管壁结垢和卡泵等问题，导致煤层气产量下降或停产，严重制约了煤层气连续稳定生产，机械捞砂方式清除井筒内煤粉和沉砂，是恢复和提高水平井煤层气产量的有效工艺技术。针对煤层气水平井机械捞砂管柱密封性差、捞砂效率低和沉砂固结等难题，优化设计并加工了爪式刮板笔尖、破砂钻头、偏心翻板和机械式旋转工具等。基于水平井机械式捞砂泵原理，将水力附加轴向力引入管柱力学模型建立了管柱−水力耦合力学模型，提出了水平井捞砂作业参数优化方法，通过工程实例分析捞砂泵单冲程往复周期对储砂管内流体流动速度和煤粉运移能力影响、翻板吸入口开放度对水力附加轴向力影响，对比分析管柱–水力耦合力学模型与常规力学模型计算管柱轴向力结果。

结果表明：(1) 爪式刮板笔尖通过结构优化提高了水平井管底沉砂破除效率，机械式旋转工具配合破砂钻头和卡簧结构解决了管壁固结沉砂破除难题，偏心翻板与球式单流阀增加了固–液两相流通过面积和密封性。(2) ø110 mm捞砂泵在单冲程往复周期60 s条件下，可运移颗粒直径不超过2.5 mm煤屑，含有少量粒径3~12 mm煤屑，能够有效运移水平井筒内堆积煤粉颗粒至储砂管内部；捞砂泵上行、下行工况下管柱轴向力比常规起下钻分别增加906.94 N、减小37.41 N，提高了捞砂作业管柱受力计算准确性。(3) 优化后的捞砂工具和工艺技术在沁水盆地10口水平井进行现场应用，单井捞砂量和单次捞砂量分别提高1.5倍、0.9倍，日均产气量和日均产水量分别增加1483.7、2.18 m³，为煤层气水平井高产稳产提供技术支撑，适用于中浅埋深煤层筛管完井和套管射孔完井的水平井及大斜度井，对推动煤层气高效开发具有重要实际意义。

Coalbed methane (CBM) horizontal wells face challenges such as sand accumulation in completion strings, pipe wall scaling, and pump sticking, leading to declined CBM production or shutdown of these wells. This severely restricts continuous, stable CBM production. Removing pulverized coals and sands from wellbores through mechanical sand bailing is recognized as an effective technique to restore and improve the CBM production of horizontal wells. To address challenges such as poor string sealing performance, low efficiency, and sand consolidation in mechanical sand bailing, this study created optimized tools including claw-shaped scraper tips, sand-breaking drill bits, eccentric flaps, and mechanical rotating tools. By introducing hydraulic additional axial force into the mechanical model of the sand bailing string based on the working principle of pumps for mechanical sand bailing in horizontal wells, this study established a string-hydraulic coupling mechanical model. Accordingly, this study proposed a method for optimizing sand bailing operation parameters. Through engineering application, this study analyzed the impacts of the single-stroke reciprocating cycle of the sand bailing pump on the fluid flow velocity in sand storage pipes and pulverized coal migration, as well as the impact of the opening degree of the flap’s suction port on hydraulic additional axial force. Additionally, this study compared and analyzed the axial forces calculated using the string- hydraulic coupling model and a conventional mechanical model.

The results indicate that claw-shaped scraper tips improve sand-breaking efficiency at the horizontal well bottom through structural optimization. The mechanical rotating tool, combined with sand-breaking drill bits and clip springs, effectively addresses the challenge of consolidated sand removal. Furthermore, the eccentric flap and ball-type check valve enhance the area of solid-liquid phases flowing through the flap and the string sealing performance. Under a single-stroke reciprocating cycle of 60 s, the ø110-mm sand bailing pump can transport coal debris with particles diameters ≤ 2.5 mm and a small quantity of coal debris with particle sizes ranging from 3 mm to 12 mm, thus effectively transporting pulverized coals accumulating within wellbores into sand storage pipes. Compared to the conventional tripping, the axial forces of the sand bailing string increased by 906.94 N and decreased by 37.41 N, respectively under upward/downward conditions of the sand bailing pump, suggesting improved calculation accuracy of forces applied to the string. Field applications to 10 horizontal wells in the Qinshui Basin demonstrated that optimized tools and technologies increased single-well and per-operation sand bailing volumes by 1.5 times and 0.9 times, respectively, with the gas and water production rising by 1 483.7 m³/d and 2.18 m³/d, respectively. The optimized tools and technologies provide technical support for stable high-yield CBM horizontal wells. They apply to horizontal and highly deviated wells with screen or perforated casing completions in coal seams at medium-to-shallow depths, holding great practical significance for efficient CBM exploitation.