振动减摩阻工具振动参数及安放位置研究

为了解决振动减摩阻工具缓解定向托压时效果不稳定的问题，研究了该工具的振动参数及安放位置。在分析托压机理的基础上，从振动管柱的受力分析入手，讨论了振动参数优选与振动减摩阻工具振动源安放位置优化的问题；以典型的三段式（直—增—稳）井眼轨道为例，编制软件对振动源安放位置的影响因素进行了模拟分析。根据理论探讨和模拟分析结果提出的振动源安放位置的优化方法，在定向井C26-12X井进行了现场试验，证明了安放位置计算方法的合理性。理论分析和现场试验结果表明，振动源输出的激振力与井身结构等因素共同影响其在钻具中的受拉极限位置和受压极限位置；提高工具输出激振力可增大有效作业范围；设计振动源的振动频率时，优先选用10 Hz以内的振动频率以延长管串使用寿命；定向中轴向力、侧向力和摩阻相互影响，下部钻柱摩阻会使钻柱整体摩阻增大，振动减摩阻工具应优先安放在靠近钻头的位置。 

Research on Vibration Parameters and Determining the Position of a Vibration Friction Reducing Tool

To solve the problem of instability in the vibration friction-reducing tool under restricted weight on bit (WOB) conditions in directional drilling,we studied the vibration parameters and setting position of the tool.We started by analyzing the primary drill string vibration,and then looked at the key vibration parameters and optimal setting positions.We then evaluated the mechanisms used to restrict the WOB.The methodology involved taking the well trajectory of a typical three-section type (straight-buildup-hold) as the example,and then developing software to simulate and analyze the influencing factors on the setting position of the vibration source.We tested the theories on Well C26-12X,specifically the placement optimization method for setting the position of the vibration.Well C26-12X was a two-spud and three-section directional well,which and the results confirmed our calculation method for the setting position.Theoretical analysis and field test results show that the exciting force of vibration source and casing program,etc.will affect the position of tensile limit position and compressive limit in the drilling string.Our results also showed that increasing the output excitation force of the tool can expand the effective operation scope.We recommend that in the design stage,it is best to maintain the vibration frequency within 10 Hz.Doing so will prolong the service life of drilling string because the axial force,lateral force and friction in the directional drilling are affected at the same time.Since the drag on the BHA will increase the integral drag to whole drilling string,the vibration friction-reducing tool should be placed near the drill bit.