针对侏罗系地层高硬度、强研磨性等特点，研究并试验了几种特殊类型的钻头。

Considering the characteristics of high degree of hardness, abrasion and high temperature of Jurassic layer, some special bits were investigated and applied.

youdao

针对侏罗系地层高硬度、强研磨性等特点，研究并试验了几种特殊类型的钻头。

Considering the characteristics of high degree of hardness, abrasion and high temperature of Jurassic layer, some special bits were investigated and applied.

youdao