PDC钻头复合冲击钻进动力学研究

Study on PDC Bit Compound Impact Drilling Dynamics

深部地层的环境温度高,岩石硬度大、研磨性强。采用PDC钻头常规钻井方式,钻头的破岩效率低、机械钻速慢。介绍了1种轴扭复合冲击破岩工具的结构和工作原理。建立PDC钻头破岩理论模型和数值分析模型,并进行对比分析,得出了常规钻进和轴扭复合冲击钻进过程中PDC钻头的运动轨迹和岩石破碎过程应力变化规律。分析发现,复合冲击作用下岩石裂纹发生快,更容易产生体积破碎,岩石表面能够形成连续均匀的破碎坑,相比常规钻进能够提速30%左右。该研究为轴扭复合冲击破岩提供了理论依据,对深井油气田开发具有重要意义。

The number of deep pumping wells in Shengli Oilfield has increased annually,and the average pump workover period is relatively short.One of the main reasons is the failure of the pump.In order to improve the service life of the deep sucker rod pump,the leakage of the ambient temperature in the deeper formations is high and the rock is hard and abrasive.The conventional drilling method using PDC bit has low rock-breaking efficiency and a slow mechanical drilling rate.The structure and working principle of an axial torsion composite impact tool were introduced.The theoretical model and numerical model for PDC bit breaking rock were established,and a comparative analysis was conducted to obtain the movement trajectory of PDC bit and the stress variation law of the rock-breaking process during conventional drilling and axial torsional composite impact drilling.It was found that under the effect of composite impact,rock cracking occurs quickly and volume crushing is more likely to occur,and continuous and uniform craters can be formed on the rock surface,which can increase the speed by about 30%compared with conventional drilling.This study provides a theoretical basis for axial-torsional composite impact rock breaking,which is of great significance to the development of deep-well oil and gas fields.