开发低煤阶煤层气的新型径向水平井技术

低煤阶煤层具有机械强度低、渗透率较高、内生裂隙发育的特点。为提高低煤阶煤层气开发效率，提出首先钻径向水平井眼，依靠多条水平井眼沟通煤层内裂隙，再根据储层条件优化水力压裂改造措施，在煤层形成的主裂缝，通过变排量措施扩展和沟通更多的内生微裂隙，以提高单井产量。为解决多井眼井底可能出砂多的问题，提出优先采用螺杆泵或电潜螺杆泵排采工艺。从阜新刘家区块和珲春盆地煤层地质条件与目前现场应用现状出发，探讨了径向水平井技术与水力压裂联合作业的可行性，提出优化两个区块的径向水平井眼布孔方式，将欠平衡钻井和“边喷边洗”的喷射技术结合，并改进常规的水力压裂改造措施，实现径向水平井技术与水力压裂改造措施有机结合，以充分发挥这两种技术的不同优势，形成一体化的煤层气开采技术。通过对径向水平井与压裂改造工艺技术的改进与联合，为低煤阶煤层气开采提供了又一新的技术方法。 

Technical analysis on radial horizontal well for development of coalbed methane of low coal rank

Coal seam of low rank has different characteristics, such as low mechanical strength, high permeability and rich endogenic fissures. A new method to improve the production of low rank coalbed methane is put forward, in which radial horizontal well is drilled earlier than hydraulic fracturing. The aim is to expand and communicate more endogenic fissures in coal seam by the radial horizontal well drilled in advance and then enhance gas production. In order to resolve the problem of sand production, screw pump or electric submersible screw pump can be adopted in preference to other pumps. According to the coal seam conditions of Fuxin Liujia block and Hunchun basin, feasibility of joint application of radial horizontal well and hydraulic fracturing is studied. It is proposed to optimize well deployment method, jointly implement under-balanced drilling and jetting with flushing. It can play their different dominant roles and develop to an incorporate coalbed methane development technology. By incorporated improvement of radial horizontal well and hydraulic fracturing, a new method to develop low rank coalbed methane is put forward.