A novel multilateral well for coalbed methane extraction was proposed in the study. There is a main wellbore at the longitudinal center of coal seam and four lateral wells at the horizontal center in the multilateral-well system. Compared with traditional drainage holes, multilateral-well system has a better performance on coalbed methane development. A hydraulic-mechanical coupling model of multilateral well was established, the pressure and permeability ratio distribution of the gas extraction process were analyzed comprehensively. The sensitivity analysis of lateral number, length distribution and intersection angle of multilateral-well system were studied. The results indicate that there is a minimum gas pressure distribution around the multilateral well and the overall permeability of coal seams increases with production time and the permeability around the multilateral well is larger than the area away from the multilateral well which induced by the gas desorb and matrix shrink. The quantity of lateral wells has a positive effect on cumulative production. When the total length of lateral wells is equal, the uniformity and symmetry of lateral length distribution are two key factors on the gas extraction performance. The minimum intersection angle has a positive effect on cumulative production. This study provides a better alternative for traditional drainage hole to obtain greater coalbed methane performance.

该研究提出了一种新型的用于开采煤层气的多边井。在多边井系统中，煤层纵向中心有一个主井眼，水平中心有四个侧井。与传统的排水孔相比，多边井系统在煤层气开发方面有更好的表现。建立了多边井水力耦合模型，对瓦斯抽采过程的压力和渗透率分布进行了综合分析。研究了多边井系统的井壁数目，长度分布和相交角的敏感性分析。结果表明，多边井周围存在最小的气压分布，煤层的总渗透率随生产时间的增加而增加，且多边井周围的渗透率大于气体解吸和驱散引起的远离多边井的面积。基质收缩。侧井数量对累计产量有积极影响。当侧井总长度相等时，侧向长度分布的均匀性和对称性是影响采气性能的两个关键因素。最小相交角对累积产量有积极影响。该研究为传统排水孔获得更好的煤层气性能提供了更好的选择。