新型扭转振动工具动力学模型与降黏特性

在油气开采过程中,随着钻井深度的增加,岩石硬度加大,井下摩擦阻力较大,钻柱系统易发生粘滑振动,这将导致部件过早发生故障,钻井作业效率低下,因此对于粘滑控制技术的研究具有重要意义。结合钻井过程中的实际工况,提出了一种新型扭转振动工具,建立了基于该工具的钻柱系统扭转振动模型以及非线性动力学模型,分别进行了算例分析与实验测试以研究工具的降粘效果。算例分析时采用控制变量法,首先在给定转盘转速、钻压的情况下,对比分析了有/无工具时的钻柱系统各部件角速度,然后在相同钻压、不同转盘转速和相同转盘转速、不同钻压的情况下,分别对钻柱系统中有/无工具时的钻头角速度进行了求解;在实验过程中,对同一口井进行了有/无工具的测试,并结合未使用该工具的相邻井录井数据,分析了该工具的降粘效果。研究结果表明：在相同工况条件下,使用该扭转振动工具,可明显消除或抑制粘滑振动,同时,适当增大转盘转速,适当降低钻压可在一定程度上抑制钻柱的粘滑振动;在误差允许范围内,理论计算结果与测试结果相符合,验证了理论模型、求解方法以及算例分析的正确性。所提出的新型扭转振动工具、建立的动力学模型与研究结果对于减少粘滑振动、提高破岩效率具有重要参考意义。

Dynamic Model and Stick-slip Reduction Characteristics of a New Torsional Vibration Tool

In the process of oil and gas exploitation, with the increase of drilling depth, the rock hardness is increased, and the downhole friction resistance is larger, the drill string system is prone to stick-slip vibration, which may lead to premature component failure and low drilling efficiency, so it is of great significance for the study of stick-slip control technology. Combined with the actual working conditions in the drilling process, a new torsional vibration tool is proposed, and the torsional vibration model and nonlinear dynamic model of the drill string system based on the tool are established. To study the stick-slip reduction effect of the tool, the case study and experimental test are carried out respectively. The control variable method is used in the case study. Firstly, given the specific values of the rotation speed of the turntable and the WOB (weight on bit), the angular velocity of each component of the drill string system with and without the tool are compared and analyzed. Secondly, both the case of " the same WOB, different turntable speeds " and the case of " the same turntable speed, different WOBs " are considered, and the angular velocity of the drill bit with and without tools in the drill string system are calculated respectively. During the experimental test, the test with and without tools were carried out at the same well, and combined with the logging data of adjacent well which did not use the tool, the viscosity reduction effect of the tool was analyzed. The results show that under the same parameters, sticky-slip vibrations can be clearly eliminated or suppressed using the new torsional vibration tool. Meanwhile, increasing the rotational speed of the turntable, and appropriately reducing the drilling pressure can inhibit the stick-slip vibration of the drill string to a certain extent. And within the allowable range of error, the theoretical calculation results are consistent with the test results, which verify the correctness of the theoretical model, the solution method and the analysis of the examples. The proposed new torsional vibration tool, established dynamic model and research results have important reference significance for reducing the stick-slip vibration and improving the rock-breaking efficiency.