新疆乌鲁木齐头屯河矿区煤层气井钻探施工技术探讨

Discussion on drilling technology of coal-bed methane well in Toutunhe mining area of Urumqi City,Xinjiang Province

新疆乌鲁木齐头屯河地区地层较为破碎、地层裂隙发育比较严重,而且煤层气井煤储层埋藏浅、煤层压力低和煤层保护难度大,这些对煤层气井的钻探提出了更高的技术要求。针对目前头屯河地区钻探施工存在的问题和难点,通过井壁稳定的力学分析方法提出井身结构应选择直井。依据空气欠平衡钻井技术与常规钻井技术对煤层的污染和破坏程度,提出采用空气欠平衡钻井技术,采用低固相或无固相钻井液。根据水泥浆顶替流态的计算方式,计算出水泥浆顶替应当采用塞流顶替。依据煤储层的保护要求提出一种新的煤储层保护方案,即使用绕煤层固井工具。

The stratum is cracked and the formation cracks are serious in Toutunhe area of Urumqi City, Xinjiang Province. But the coal-bed methane wells are buried in shallow stratum. Because of low coal seam pressure and the big difficulty in coal seam protection, it requires higher technology on the drilling of coal-bed methane wells. Aiming at these problems and difficulties in drilling construction in Toutunhe area, it is proposed that the wellbore structure should be the vertical well through the mechanics analysis of borehole stability. Based on the pollution and damage degree caused by the air under-balanced drilling technique and the conventional drilling technique, the air under-balanced drilling technique is proposed and low solid or solid free drilling fluid should be used. According to the calculation method of cement slurry displacement fluid flow, the cement slurry displacement should be the plug flow displacement. According to the protection requirement of coal reservoir, there is a new coal reservoir protection scheme,which is accomplished by around the coal seam cementing tool.