延川南煤层气田经过6年多开发实践，认识到储层改造体积小导致的缝控储量规模不足是煤层气井低产主因之一。气田呈现出低效井井数占比高、贡献产量小的生产特征。为改善气田开发形势，急需开展低效井增效开发技术攻关。理论研究表明，水平应力差异系数(K)越小，水力压裂越易形成复杂缝网；压裂施工产生的诱导应力能够改变储层应力状态，降低K值；多次压裂施工能够多次诱导储层主应力重定向，有助于低渗煤层形成复杂缝网系统。以鄂尔多斯盆地东南缘延川南煤层气田稳产期短、剩余储量丰富的低产气井为研究对象，开展以梯次提高排量、逐渐增大前置液量、组合加入支撑剂为主要特征的多次压裂增效开发技术现场试验。应用后，监测的裂缝缝长是单次施工产生的缝长3倍以上，裂缝形态由单一裂缝转向复杂缝网，有效扩大储层改造体积；通过多次组合加砂实现缝网有效支撑，在深部煤储层建立高效导流通道。复产后，试验井气液平均日产出量分别提高5倍、7倍，评估最终可采储量增加5倍左右，提高煤层气单井产量和最终采收率，实现低效煤层气井高效治理，增产效果显著。在随后推广应用的22口煤层气井中，实现单日平均产量和最终累计产量的双突破，证实多次压裂增效开发技术能够提高深部煤储层的缝网复杂程度并实现有效支撑、高效导流，是剩余储量丰富的低产老井行之有效的治理举措。

After more than six years development and practice in the South Yanchuan coalbed methane field, it has been recognized that lack of fracture-controlled reserves caused by small volume of reservoir reconstruction was one reason for low yield. There is an urgent need to explore efficient development technologies for low-efficiency wells. Theoretical study shows the smaller the horizontal stress difference coefficient (K) is, the easier it is for hydraulic fracturing to form a complex fracture network. The induced stress generated by fracturing can change stress state of reservoir and reduce the K value. Multiple fracturing operations can repeatedly induce the redirection of reservoir principal stress, which helps to form complex fracture network in low permeability coal seams. This paper takes the low-yield wells with short stable yield period and abundant remaining reserves in the field in southeastern margin of Ordos Basin as the research object. The field test of multiple fracturing efficiency enhancement development technology was carried out. It was characterized by increasing displacement by steps, gradually increasing amount of prestage fluid and adding proppant in combination. After the application, the monitored fracture length is more than 3 times that of a single construction, and the fracture morphology changes from a single fracture to a complex fracture network, which effectively expands volume of reservoir reconstruction. The effective support of fracture network was realized by adding sand for times, and the efficient diversion channel was established. After the resumption, the average daily gas-liquid yield was increased by 5 times and 7 times respectively, and the estimated ultimate recovery were increased by about 5 times. The effect of increasing production is remarkable. In the 22 coalbed methane wells that were subsequently popularized and applied, double breakthroughs were achieved in the average daily production and the final cumulative production, which proved that the multiple fracturing and efficiency-enhancing development technology can improve the complexity of the fracture network of deep coal reservoirs and achieve effective support and high efficiency, which is an effective measure for low yield wells with abundant remaining reserves