某矿区地层属第三系组底部层（见某矿区地层综合柱状图），绝大部分是质软的粘土，构造较为复杂；可钻性3级左右；粘土的吸水性强，极易造浆；膨胀系数大，钻孔缩径现象较为严重。在钻进过程中，经常发生糊粘、堵水现象，甚至蹩泵导致高压送水管破裂，影响钻进。特别是在矿心采取方面，由于该矿呈结核状，含于松散、质软的劣质煤层中，厚约0.8米，易被冲洗液冲刷流失，稍有疏忽，就有打丢矿层，造成钻孔 The strata of a mining area belongs to the bottom layer of the Tertiary Formation (see the integrated column diagram of the strata in a certain mining area), most of which is soft clay with a complicated structure. The drillability is about 3 grades. The clay has strong water absorption and can easily make pulp ; Expansion coefficient, bore diameter reduction is more serious. In the drilling process, often happen paste sticky, water blocking phenomenon, or even a bad pump lead to high pressure pipe burst, affecting drilling. Especially in mining, due to the mine was nodular, contained in loose, soft, poor quality coal seam, about 0.8 meters thick, easy flushing fluid erosion loss, a slight negligence, there are hit throwing ore, resulting in drilling hole