煤层气多分支水平井钻井技术在樊庄区块的应用
Application of CBM multi-branch horizontal well for drilling technology in Fanzhuang Block
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摘要: 基于樊庄区块3号煤层的地质和力学特征,该区块适于采用多分支水平井钻井技术开发煤层气。分析了煤层气多分支水平井存在的安全钻进及储层保护、井眼轨道控制、井下复杂事故和新式钻井工具及仪器等技术难点。通过2口井现场实施情况表明,在煤层的水平段及分支段钻进过程中,宜采用近平衡钻井,钻井液以清水为主;尽量保持井眼轨迹沿煤层中上部靠近煤层顶板位置钻进,且实施快速钻进;减少煤储层在钻井液中的浸泡时间,以利于保持煤层井壁稳定,减少煤储层的伤害及煤层坍塌危险;水平及分支段中,减阻短节(AG-itator)的使用能降低井下摩阻,避免钻柱的螺旋屈曲;钻遇断层、破碎带时要提前完钻,防止井下复杂事故的出现。Abstract: Based on analysis of the basic geological and mechanical features of No.3 coalbeds in Fanzhuang Block,it is found that the multi-branch horizontal well is fit for No.3 coalbeds in this block.The technology difficulties of that wells drilled in Fanzhuang Block are analyzed,such as safety drilling and reservoir protection,well path con-trol,complex accident,also new type well drilling tools and equipments.Through actual drilling engineering of two wells,some conclusions can be derived.It’s a better way to use near balance drilling(drilling fluid is water) when drilling in horizontal and branch coalbed sections;keeping well path near to roof of coalbeds and speeding drilling;reducing the time of coalbeds dipping in drilling fluid;making use of AG-itator in horizontal sections and branch sections;finishing drilling ahead of schedule when drilling across faults and fractured zones.