PDC磨损齿切削破岩过程的实验研究

为探究深部钻井PDC钻头切削齿在磨损状态下的切削破岩过程,选取深部钻井PDC钻头上不同磨损程度的PDC齿开展单齿切削实验,借助应力测试系统、高速摄影机和热红外成像仪分析磨损齿的受力状态、温度变化规律以及岩石裂纹扩展过程。结果表明,与未磨损齿相比,磨损齿所受切削力更大、温度变化更明显,且更易产生大体积岩屑,这将导致钻头在井下振动加剧,磨损急剧加快,严重影响其使用寿命;切削花岗岩时切削力和温度大幅上升的问题更加突出,但更容易发生体积破碎,产生较大块的块状岩屑。研究成果将有助于重新认识真实井底磨损齿切削破岩及温度变化规律,并为钻头设计及井下寿命评估提供重要参考。

A Study on the Mechanism and Heat Generation Law of PDC Wear Tooth Cutting

To explore the cutting process of deep drilling PDC bit cutting teeth in the wear state, the single tooth cutting experiment is carried out by selecting PDC cutting teeth with different wear degrees on the deep drilling PDC bit. The stress state, temperature change law and crack propagation process are analyzed by stress test system, high speed camera and thermal infrared imager. The results show that the cutting force, temperature change and large volume cuttings are more obvious than the non-wear teeth, which will lead to the outburst of drill bit vibration and the sharp acceleration of wear, seriously affecting its service life. On the other hand, when cutting granite, the problem of cutting force increase and heating up is more prominent, but volume breakage is more likely to happen and produce larger block cuttings. The research results will help to re-understand the rock breaking and temperature variation law of real bottom wear teeth, and provide important reference for bit design and downhole life evaluation.