工程勘察用非均质热压金刚石钻头试验研究

Experiment on Heterogeneous Hot-pressing Diamond Bit for Geo-technical Investigation

摘要:

工程勘察在同一个钻孔中需要面对不同风化程度的岩石层，并可能遇到不同粒径与胶结性的卵砾石层。因地质条件较为复杂，工程勘察钻进过程中容易产生憋钻、糊钻等现象，岩心采取率低。针对工程勘察钻进特点，为提高金刚石钻头对地层的适应性和钻进效果，并提高岩心采取率，设计了2种新型非均质热压金刚石钻头。该结构将每个工作齿分成主、辅工作层两部分，可以使钻头既具有PDC钻头破岩的特征，又能体现孕镶金刚石钻进的特色，并提高钻头对地层的适应性。现场试验表明，该结构的钻头在风化岩层和基岩中的平均钻进时效达2.68 m，钻头使用寿命平均达48.70 m；对比电镀金刚石钻头，钻进速度提高约21%，使用寿命相当。

Abstract:

During geo-technical investigation, rock formation with different weathering degrees, and bouldery formation with different particle sizes and cementation can be encountered in drilling of the same borehole. The complexity of geological conditions may easily lead to such phenomena as bit bouncing, bit balling, resulting in low core recovery. To improve the adaptability and drilling efficiency of diamond bits, two kinds of diamond bits with heterogeneous structures were designed and manufactured according to the characteristics of geotechnical investigation. In the heterogeneous structure, every single cutter is divided into two parts: main and auxiliary working layers, which allows the diamond bit behaving like both the PDC bit in rock fragmentation and the impregnated diamond bit in drilling, improving the adaptability of the diamond bit to different formation. Field testing indicates that the new heterogeneous diamond bit can achieve 2.68m/h average rate of penetration, and 48.7m average bit service life in weathered rock and bedrock. Compared with ordinary electroplated diamond bits, the rate of penetration is improved by 21%, while the service life is more or less the same.