五宝场硬塑性地层斧形曲面PDC齿破岩性能研究

Study on the rock breaking performance of axe-shape cambered PDC cutters in the hard plastic formation in Wubaochang

摘要:

为解决川东油气钻井中五宝场沙溪庙组硬塑性地层PDC钻头磨损严重、起下钻频繁的问题，开展了斧形曲面PDC齿在硬塑性地层破岩性能的研究。首先采用X射线衍射试验与三轴力学试验分别获取该地层岩石性质和力学参数，然后采用有限元仿真与试验相结合的方法开展斧形曲面PDC齿破岩性能研究。研究结果表明：斧形曲面PDC齿主要以剪切、挤压、犁切共同作用破岩；相较于常规PDC齿，斧形曲面PDC齿有更强的吃入岩石的能力和稳定性，能有效减小钻头异常振动，提高钻头寿命，并在不同磨损高度（0~3 mm）时，破岩比功降低2.2%~8.2%；根据试验得到斧形曲面齿较常规齿破岩性能提高了11.39%，且试验与仿真平均切削力误差仅为7.46%，验证了仿真模型的正确性。本研究表明斧形曲面PDC齿在硬塑性地层对提高破岩性能具有重要意义。

Abstract:

In order to solve the problem of severe wearness and frequente tripping work in the hard plastic strata of Shaximiao Formation in Wubaochang， the research on the rock breaking performance of an axe-shape cambered PDC cutters is made. Firstly， the X-ray diffraction test and triaxial mechanical test are used to obtain the rock properties and mechanical parameters of the formation， then the finite element simulation and test are combined to study the rock breaking performance of the axe-shape cambered PDC cutters. The results show that the axe-shape cambered PDC cutters mainly break rock by the combined action of shearing， extrusion and plowing. Compared with the conventional PDC cutters， the axe-shape cambered PDC cutters have stronger rock-breaking ability and stability， which can effectively reduce the abnormal vibration of the bit， improve the bit life， and the rock breaking mechanical specific work can be reduced by 2.2%~8.2% at different wear height （0~3 mm）. According to the test results， the rock breaking performance of the axe-shape cambered PDC cutters is higher than that of the conventional cutters by 11.39%， and the average cutting force error between test and simulation is only 7.46%， which verifies the correctness of the simulation model. This study shows that the axe-shape cambered PDC cutters are of great significance in improving the rock breaking performance in hard plastic formation.