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钻探中广泛使用的喷反钻具,其结构和维护简单,通常有一个与钻具轴线平行的喷咀.但是这种钻具有不少缺点,例如,回次进尺有限,在钻进裂隙和破碎的岩矿层时更为如此.这是由于随着岩心管内岩心长度及其破碎程度的增加而使流体阻力增大,从而降低了抽吸效率和返水量.结果岩心在钻头中磨耗,不能进尺.抽吸效率和岩心长度的关系见下式:U=U_O(1.3-0.02T)(1-0.15φh)式中:U_O是在清水洗孔和岩心管内没有岩
Drilling is widely used in the drilling and drilling tools, its structure and maintenance is simple, usually with a drilling axis parallel to the nozzle, but this drill has many shortcomings, such as back to the limited footage, in the drilling cracks and broken This is due to the fact that as the length of the core in the core tube increases and its degree of fragmentation increases, the fluid resistance increases, reducing the pumping efficiency and the amount of return water.Results The core is worn in the bit and can not scale. The relationship between suction efficiency and core length is given by the following formula: U = U_O (1.3-0.02T) (1-0.15φh) where: U_O is the area where no rock