金刚石钻头与牙轮钻头钻井特点对比分析

Comparative analysis of drilling characteristics of dia- mond bits and roller bits

金刚石钻头与牙轮钻头在钻井中各自有着重要作用，两种钻头由于结构不同，其破岩机理、钻进特点、使用条件均不同。牙轮钻头主要靠敲击、压碎破岩、辅以剪切破岩；金刚石钻头主要靠剪切、切削破岩、辅以压碎破岩。金刚石钻头的钻压小、转速高、排量小，有利于纠斜防斜，可在高密度钻井液条件下使用，但它不能有效地钻进含燧石、黄铁矿和硅质的不均质坚硬地层。所以，在钻井中，应根据两种钻头各自的特点，采用“衔接使用法”将两种钻头配合使用，使其发挥最佳破岩效果。

During drilling,both diamond bits and roller bits have played an important role.Because of different structures,rock breaking mechanism,drilling features and application conditions of two kinds of bits are different.Roller bits mainly break the rocks by knocking and crushing,aided with shearing.While diamond bits break formation through shearing,cutting and crushing.Diamond bits require lower WOB,high rotary speed and small flow rate,useful for hole straightening and inclining prevention,and it can be used high-density drilling fluids.But diamond bits can′t effectively drill heterogeneous hard formations which contain chert,pyrite and silicastone.So,based on the characteristics of two kinds of bits,they can be well used in combination to achieve optimum rock breaking results.