煤层气径向水平井压裂室内试验与产能数值分析

Laboratory Testing and Productivity Numerical Simulation for Fracturing CBM Radial Horizontal Wells

煤层气径向水平井压裂工艺,即先在目标煤层钻成单层或多层径向水平井、再进行水力压裂改造,有望成为一种解决我国煤层气单井产量过低问题的有效手段。为研究该工艺在煤层中的压裂效果,采用大型真三轴水力压裂试验设备对径向水平井压裂过程进行了物理模拟,得到了3种裂缝形态,并依据试验结果分析了井眼参数对裂缝起裂与扩展的影响规律;同时,采用油藏数模软件对径向水平井压裂后的煤层进行建模,对不同完井方式的产能对比,论证了径向水平井压裂对于煤层气高效开采的巨大潜力,指出径向水平井压裂应当以"一平多纵"的缝网形态为设计目标,并给出了具体的工程设计建议,为该技术在煤层气开发中的应用提供了理论依据。

Fracturing to CBM（coalbed methane）radial wells is expected to be an effective means in China for hydraulic fracturing stimulation after one or multiple radial wells are drilled in the target coal seams.In order to understand the fracturing effect ont he coal seam,aphysical simulation was carried out on the fracturing process of radial wells by using large-scale true tri-axial hydraulic fracturing test equipments,and consequently three fracture morphologies were obtained.The influential rules of borehole parameters on the fracture initiation and propagation were analyzed on the basis of the experiment results.In addition,a model for coal seams stimulated by the radial horizontal well fracturing was constructed by using numerical reservoir simulation software.The great potential of radial horizontal well fracturing in high-efficiency CBM exploitation was demonstrated by comparing the productivity in different well completion modes.It was proposed that a radial well fracturing network should be formed as one horizontal fracture and multiple vertical fractures.Finally,the specific engineering design suggestion was put forward,and provided a theoretical basis for the application of radial fracturing to the development of coalbed methane.