沁水盆地南部低成本煤层气钻井完井技术

沁水盆地南部煤层气资源丰富,是中国第一个煤层气商业开发效果较好的区块.沁水盆地南部煤层气主力开发层系3号煤层埋藏较浅且地层压力稳定,采用小钻机、二开井身结构、清水或空气钻进的低成本钻井工艺可满足煤层气开发要求.考虑煤层气钻井地质、排水采气和低成本施工工艺等煤层气开发的特殊要求,建立了煤层气丛式井轨迹优化模型,并深入研究了四井组丛式井轨迹优化设计、钻具组合等.对低成本直井和丛式井钻井工艺的经济效益进行了评价,结果表明,采用小钻机、空气或清水钻进和丛式井低成本钻井完井工艺可实现煤层气的低成本高效益开发,四井组丛式井比直井开发模式更为节约,可节约钻井成本的4.518%.

Low-cost drilling and completion techniques for coalbed methane in southern Qinshui Basin, Central China

The southern Qinshui basin is rich in coalbed methane (CBM), it is the first area that obtained good results in the commercial development of CBM in China. No.3 layer, the main producing zone, is buried shallow and the formation pressure is stable. So the low-cost drilling techniques, such as the small rig, second-spudding well structure and air or clean water drilling can satisfy the production demand. Based on the special requirements in the CBM development, such as drilling geology, draining water during gas production and low cost technology, this article establishes the optimum trajectory model of cluster wells for producing CBM, and makes a in-depth study on the optimum design of well trajectory and the composition of drilling tool. It also evaluates the economic benefits of low-cost vertical wells and four-well-composition cluster wells. The result indicates that CBM can be produced with high profits using the low-cost drilling and completion techniques. The four-well-composition cluster well technique is cheaper than the vertical well and may save 4.518% of the total drilling cost.