基于正交切削理论的PDC钻头切削齿动态破岩温度分布

Dynamic rock-breaking temperature distribution of PDC bit cutter based on orthogonal cutting theory

在油气钻探过程中,PDC钻头的动态破岩行为表现出高度的非线性特性,这一过程涉及复杂的位移场与温度场的耦合问题。在切削过程中,由摩擦产生的热量在切削齿上积聚,导致切削系统的温度显著上升。过高的温度会加速切削齿的磨损,甚至可能导致切削齿失效,从而对钻井效率产生负面影响并增加钻井成本。为了预测和分析PDC钻头切削齿破岩过程中的温度分布规律,并揭示其动态破岩特性,基于正交切削理论和岩石弹塑性力学,构建三维耦合位移场-温度场模型,用以模拟PDC钻头切削齿在破岩过程中的非线性动力学行为,分析不同切削参数和结构参数下切削力的大小和温度分布规律。研究结果表明:切削齿的高温区位于切削刃附近的椭圆区域内,且角度在以切削刃为中心的90°~230°范围内;最佳的切削深度为0.001 m,前倾角优选为7.5°。此类参数设定可降低切削齿的磨损,同时避免高温失效,从而最小化切削力和最高温度。本文所提方法为研究PDC钻头整体结构设计和切削齿热损伤提供了理论依据和分析方法,使设计出的PDC钻头对复杂地层具有更好的适应性。

In the process of oil and gas drilling,the dynamic rock-breaking behavior of PDC bit exhibits highly nonlinear characteristics,which is characterized by a complex coupling between displacement field and temperature field.During the cutting process,the heat generated by friction accumulates on the cutter,leading to a significant increase in the temperature of the cutting system.Excessive temperatures can accelerate wear of the cutter,and may even cause it to fail,which negatively impacts drilling efficiency and increases drilling costs. In order to predict and analyze the temperature distribution of PDC bit cutters during rock-breaking and reveal its dynamic rock-breaking characteristics, a three-dimensional coupled displacement field-temperature field model is proposed based on orthogonal cutting theory and rock elastoplastic mechanics. This model is used to simulate the nonlinear dynamic behavior of PDC bit cutters during rock-breaking. Furthermore, the cutting force and temperature distribution under different cutting parameters and structural parameters are analyzed. The results indicate that the high-temperature zone of the cutter is located in an elliptical area near the cutting edge, with an angle ranging from 90° to 230° centered on the cutting edge. For optimal cutting depth of 0.001 m and a preferred pitch angle of 7.5°, cutting force and maximum temperature are minimized, which helps to reduce cutter wear while avoiding high-temperature failure. It reduces drilling costs while maintaining efficient drilling operations. This method provides a theoretical basis and analysis method for the study of PDC bit structure design and cutter thermal damage, which is helpful to design PDC bit structure more suitable for complex formation characteristics.