封隔器仿生鳞片齿卡瓦微牙痕及稳定性研究

Study on Micro-tooth Marks and Stability of Bionic Scale Tooth Slip of Packer

传统封隔器卡瓦在长期锚定套管内壁时,卡瓦牙与套管接触面会形成咬痕,过大的咬入深度可能会导致套管内壁遭到破坏,甚至失效。通过建立常规齿和仿生鳞片齿卡瓦牙与弹性套管半空间体接触模型,推导出在弹性区域和塑性区域内卡瓦牙与套管相互作用力和压入深度的关系。并且对比常规齿卡瓦牙型结构参数,构建了仿生鳞片齿卡瓦牙型结构参数,建立了锥体-卡瓦-套管三维接触有限元模型,采用有限元数值模拟和正交优化相结合的方法得出仿生鳞片齿卡瓦最佳牙型结构参数为:卡瓦牙倾角β′=90°、卡瓦锥角γ′=15°、卡瓦牙顶角α′=72°、鳞片齿长半轴R=5 mm、鳞片齿短半轴r=3 mm。研究结果表明:优化后的仿生鳞片齿卡瓦比优化后的常规齿卡瓦在套管内表面产生的应力减小了7.8%,牙痕深度减小了18.6%,证明了仿生鳞片齿卡瓦的微牙痕效果。由数值模拟得出不同摩擦因数下常规齿卡瓦和仿生鳞片齿卡瓦与套管接触压力的合力随时间变化曲线,摩擦应力的合力随时间变化曲线和接触面积随时间变化曲线,从曲线可以看出仿生鳞片齿卡瓦的稳定性比常规齿卡瓦更优。研究结果可为封隔器的研究与应用提供参考。

When conventional packer slip anchors the casing wall for a long time,there will be bite marks on the contact surface between slip teeth and casing.Excessive bite depth may cause the casing wall to be damaged or even fail.A contact model between conventional teeth slip or bionic scale teeth slip and elastic casing half space was established to derive the relationship between the pressing depth and the interaction force between slip teeth and casing in elastic and plastic areas.In addition,compared with the conventional tooth slip structure parameters,the bionic scale tooth slip structure parameters were constructed,and a three-dimensional contact finite element model of cone-slip-casing was established.By using finite element numerical simulation and orthogonal optimization methods,the optimal tooth structure parameters of bionic scale tooth slip were obtained as follows:slip angle β′=90°,slip cone angle γ′=15°,slip apex angle α′=72°,scale tooth long semi-axis R=5 mm and scale tooth short semiaxis r=3 mm.The results show that the stress of the optimized bionic scale tooth slip on the inner wall of the casing is reduced by 7.8% and the depth of tooth marks is reduced by 18.6% compared with the optimized conventional tooth slip,which proves the micro-tooth mark effect of the bionic scale tooth slip.By means of numerical simulation,the curves of the resultant force of contact pressure with time,the resultant force of friction stress with time and the contact area with time between conventional tooth slip or bionic scale tooth slip and casing with different friction factors were obtained.It can be seen that the stability of bionic scale tooth slip is better than conventional tooth slip.The research results provide references for the research and application of packers.