煤系钻探岩石可钻性分级方法的研究

STUDY OF THE METHOD OF CLASSIFICATION OF DRILLABILITY OF ROCKS IN THE COAL—BEARING FORMATIONS

研究了煤系中采用硬质合金钻进工艺时岩石可钻性分级的指标体系及测试方法;研制了一套能在野外流动条件下进行岩石可钻性分级测试的轻便仪器及工具。在7项分级指标体系中,压入强度、研磨性、塑性系数和用微型针状硬质合金钻头测试“微钻钻速”是首次应用,尤以用小试样测试“压入强度”及用微型针状硬质合金钻头测试“微钻钻进速度”两项指标能有效地反映煤系软岩石分级档次,可以弥补用微型孕镶金刚石钻头在6级以下较软岩石中无法钻进或达不到钻进指标的不足。

The criteria system of classification of drillability of rocks in the coal-bearing formations, as well as the analytical and testing methods, using cemented carbide drilling method are studied.In addition, the portable analytical and testng instruments, equipments and tools used in the field condition are manufactured.Among the 7 items of criteria system of classification, the indentation strength, the grindability, the plasticity coefficient and the drilling rate measured using the mini-needle cemented carbide bit are first applied in the classification of drillability of rocks.Especially, two items using mall sample to test the 'indentation strength' and using the mini-needle cemented carbide bit to measure the 'drilling rate' can reflect the category of classification of rocks in soft coal-bearing formations effectively.Using the mini-needle cemented carbide bit can make up for the defects that using min-iimpregnated diamond bit can not drill in soft coal-bearing formations below the 6th category or is difficult to reach the stipulated criterion of 'drilling rate'.