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

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。

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 control, 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.