直井油管柱扶正器间距设计研究

为了避免生产过程中直井的油管柱受井底的轴向载荷失稳变形从而导致油管柱与井筒发生磨损，防止油管柱发生失稳变形引发事故，安装扶正器是有效的措施。针对扶正器的安装主要依靠经验，缺乏理论分析指导，既容易导致事故发生又增加成本的问题，基于封隔器—油管柱的实际受力及变形分析，建立了油管柱失稳力学模型，推导了直井中相邻扶正器临界失稳长度的计算公式，得出了扶正器的合理间距，并利用MATLAB进行实例的分析计算。结果表明:从中和点到井底，扶正器的布置间距呈现减小趋势；井口油压的降低导致油管柱临界失稳长度变小，使得扶正器的布置间距更加密集。该间距设计对油管柱扶正器的现场布置有实际的指导意义。

Study on spacing design of tubing string centralizer in vertical well

The instability and deformation of tubing string caused by the axial load at the bottom of well in the production process of vertical well will lead to the wear of tubing string and wellbore. In order to prevent the accidents caused by the instability and deformation of tubing string, it is an effective measure to install the tubing string centralizer. Aiming at the problems that the installation of centralizer mainly relies on experience and lacks of theoretical analysis and guidance at present, which is easily to cause the accidents and increase the cost, an instability mechanics model of tubing string was established by the force and deformation analysis of packer - tubing string. The calculation formula of critical instability length for the adjacent centralizers in vertical well was deduced, and the reasonable spacing of centralizer was obtained. Finally, MATLAB software was utilized to carry out a case study. The results showed that the arrangement spacing of centralizer decreases gradually from the neutral point to the bottom. The decrease of oil pressure at wellhead will lead to the decrescent critical instability length of tubing string, which makes the arrangement spacing of centralizer denser. The design of spacing has practical guiding significance for the worksite arrangement of tubing string centralizer.