direct circulation meaning in English

环环流
正环流
正循环
直接环流

Abstract : the paper presented a kind of drilling hole method that adopted direct circulation and percussion drilling , casing and cliff - protection by mud . the method applied in the complex gravel layer which has the trend to emerge cave - in and drop from the drilling wall
文摘:介绍一种在砂卵石地层层厚复杂、孔壁易掉块、易坍塌的钻孔的成孔方法? ?正循环回转与冲击钻进、套管与泥浆护壁成孔。