【作者】 程军；

【导师】 吴敏； 吴奋；

【作者基本信息】 中国地质大学 ， 控制科学与工程， 2020， 硕士

【摘要】 深部地质资源及非常规能源的开发与利用已经成为未来的趋势。在深部地质钻进过程中,钻柱系统粘滑振动广泛存在,会导致钻柱、钻头过早失效,井眼轨迹恶化,稳定器过度磨损,钻速下降等一系列问题,如何有效地抑制粘滑振动是一个亟待解决的关键问题。因此,开展钻柱系统建模及振动抑制研究对于提高钻进效率、降低钻进成本具有重要的意义。论文主要的研究工作如下:(1)考虑到钻柱系统的多单元组合特性与时变长度特性,结合有限元建模思路与线性变参数技术,提出一种钻柱系统多自由度-变参数离散模型。首先,分别从钻柱系统井上、井中及井下部分分析钻柱系统特性,获取影响钻柱动力学的主导部分,并对钻进工艺与钻柱系统进行一定的限制与简化。基于有限元建模思路,将钻柱视为一系列的弹簧-质量-阻尼单元组合,同时考虑钻柱长度的时变特性,建立以钻杆长度为变化量的钻柱多自由度-变参数离散模型。为了验证提出模型的有效性,基于有限元软件,构建钻柱高阶有限元模型,并与之进行对比分析;最后分别考察钻柱系统多自由度-变参数模型在不同钻杆长度下的时频域响应以及粘滑振动现象。(2)针对井场具体的性能需求以及测量、控制单元的限制,基于井上转速与顶驱,结合增益调度控制技术,提出以钻杆长度为调度参数的钻柱粘滑振动主动抑制方法。首先系统地抽象出钻柱系统粘滑振动抑制控制问题,并结合期望的控制性能给出控制目标。接着基于提出的钻柱多自由度-变参数模型,结合H_∞控制与增益调度技术,建立闭环控制系统。借助基于网格的LPV控制器求解方法,以闭环系统最小诱导2范数为优化目标,给出高阶增益调度控制器的求解步骤。此外,为了保证控制器在实际中的有效实施,也给出高阶增益调度控制器的降阶方案。最后,与现有文献中的粘滑振动抑制方法进行系统的对比与分析,仿真结果表明,本文所设计的高阶及降阶增益调度控制器在钻柱长度存在较大变化的情况下仍然能够保持良好的控制性能。(3)设计一种以双电机拖动系统为硬件、以TwinCat实时控制系统为软件、以数值算法模拟钻柱动力学的实验方案。给出该实验系统的硬件结构、软件结构以及离散降阶增益调度控制器与钻柱动力学数值算法的实现,同时也分析该实验方案的合理性。实验结果说明所设计增益调度控制器的有效性。更多还原

【Abstract】 There has been a trend in terms of the exploration and utilization of deep geological resources and non-conventional energy.In the deep drilling process,stick-slip vibrations of drill-string systems appear frequently and extensively,which induce the failure of drill-string and drill bit,deterioration of drilling trajectories,excessive wear of stabilizers,and so on.How to effectively suppress stick-slip vibrations has become an imperative problem.Therefore,conducting the research on drill-string characteristics and the correspondent suppression methods has significant importance regarding improving drilling efficiency and reducing drilling cost.The primary work of the thesis lies in the following(1)Considering the characteristics of the drill-string in terms of the multi-units combination and length-varying,this paper proposes a drill-string multi-DOFs parameter varying discrete model which combines the idea of finite element model(FEM)and linear parameter varying technique.Firstly,we analyze the features of drill-string systems from 3 parts,i.e.,top part,middle part and bottom part of drill-string,and then we obtain the dominant components which have significant impact on drill-string dynamics.We also make some simplifications on the drill-string system considered in this thesis.Then,the drill-string is seen as the combination of a series of spring-mass-damper units,and we develop a multiple DOFs length varying drill-string model based on linear parameter varying(LPV)technique.In order to verify the effectiveness of the proposed model,we make a comparison with a high-order drill-sting FEM model developed by the FEM software.Finally,we study the time-frequency domain responses and stick-slip phenomenon of drill-string with regards to different length of drill pipes.(2)Given the available measurements,drive units,and the specific performance requirements in the common drilling practice,we combine the gain-scheduling technique and propose an active rejection method,which treats the length of drill-pipes as scheduling parameter for suppressing stick-slip vibrations.We firstly systematically abstract the suppression control problem of stick-slip vibrations,and present the control objectives by combining the desired performance.Based on the proposed drill-string multi-DOFs LPV model,we develop the closed-loop system with the aid ofH_∞control and gain-scheduled technique.Leveraging the gridding-based LPV controller,we consider the least induced 2-norm of closed-loop control system as optimization target and present the procedures for solving the gain-scheduled controller.Meanwhile,in order to implement the developed controller effectively in real drilling practice,we also present the reduction scheme of high-order gain-scheduled controller.Finally,a series of simulations and comparisons show that the designed high-and reduced-order controller can preserve satisfactory performance in spite of the large variation of the length of drill-string.(3)This paper devises a feasible experimental scheme that uses dual-motor driving system as hardware,the Twin Cat real-time control system as software,and numerical algorithms as drill-string dynamics,to verify the effectiveness of the proposed controller in the real test.Then,we respectively present the hardware configuration,software configuration,and the implementation of discrete reduced gain-scheduled controller and the drill-string dynamics.And we also analyze and verify the rationality of the proposed experimental scheme.Experimental results illustrate the effectiveness of the proposed gain-scheduled controller.更多还原