金刚石取心钻头干钻热特性试验研究

Experimental study on the thermal characteristics of dry drilling of diamond coring bits

摘要:

干式钻进对环境的影响很小，在没有冷却介质的情况下，对于钻进一些遇水或钻井液发生反应或者产生新的污染等情况而言，可有效解决钻孔取心问题，因此，该方法是地外天体采样的重要手段之一。然而以往地外天体钻头多为硬质合金钻头，对于钻进坚硬岩层具有一定的局限性。金刚石钻进是一种比较先进的回转钻进技术，在油气勘探和地质勘查中应用广泛，是钻进坚硬岩层的利器。本文针对坚硬花岗岩开展了金刚石钻头的干式钻进试验研究，探讨了钻进参数及钻头种类等对钻进过程热特性的影响。研究结果显示：PDC钻头的升温速率较常规表、孕镶取心钻头更低，约为常规孕镶钻头的1/2；PDC取心钻头在适宜的工艺参数下，可实现花岗岩的干式钻进；干式钻进中转速对金刚石钻头升温的影响较大，且呈现非线性增长趋势；钻头在空气中的降温曲线整体呈现指数下降趋势。在300 ℃降温至100 ℃过程中，降温速率≥60 ℃/min。该研究成果可为科学设计与合理使用干式钻进钻头提供依据。

Abstract:

Dry drilling has little impact on the environment. In the absence of cooling medium， it can effectively solve the problem of borehole coring when drilling some water or drilling fluid reacts or produces new pollution， so this method is one of the important means of exoplanets sampling. However， exoplanets object drill bits were mostly alloy drill bits， which had certain limitations for drilling into hard rock formations. Diamond drilling is a relatively advanced rotary drilling technology， which is widely used in oil and gas exploration and geological exploration， and is a powerful tool for drilling hard rock formations. In this paper， the dry drilling tests of diamond drill bits were carried out for hard granite， and the influences of drilling parameters and bit types on the thermal characteristics during the drilling process is discussed. The results show that： （1）The heating rate of PDC drill bits is lower than that of conventional diamond coring bits， which is about 1/2 of that of impregnated diamond bits； （2）PDC coring bits can be a way for the dry drilling of granite under suitable process parameters；（3）The rotary speed has a great influence on the temperature rise of diamond bits in dry drilling， and it shows a nonlinear growth trend；（4）The cooling curves of drill bits in air show an exponential downward trend. During the cooling from 300°C to 100°C， the cooling rate≥60°C/min. The research results can provide a basis for the scientific design and rational use of dry drilling bits.