气井环空带压条件下橡胶-管柱接触面干摩擦影响因素分析

Analysis of Influencing Factors on Dry Friction of Rubber Pipe String Interface under Annular Zone Pressure in Gas Well

由于气井不压井作业过程中对泄漏事故零容忍,井口密封关系到气井作业的可靠性和安全性,成为不压井技术的关键。接触干摩擦以及剪切应力是橡胶-管柱密封副损坏的直接原因。建立橡胶-管柱刚-柔接触干摩擦力学模型,分析得到温度、速度、压力是影响干摩擦特性的重要因素。建立橡胶Mooney-Rivlin模型,对丁腈橡胶在干摩擦工况下的摩擦磨损情况进行ABAQUS有限元模拟,对比单一因素变化及耦合工况下剪切应力对橡胶的损坏规律。研究表明:单一影响因素时,摩擦生热随着相对滑动速度的加快,使接触面温度升高,导致橡胶硬度变化,加剧磨损;耦合工况下速度对剪切应力影响最大。

Under the consideration of zero tolerance to leakage accident in non-compaction operation of gas well,the reliability and safety of wellhead sealing to gas well operations has become the key to non-compaction technology.The contact dry friction and shear stress are the direct causes of damage of rubber-string seal pairs.In this paper,a mechanical model of rubber-string rigid-flexible contact dry friction was established.The temperature,velocity and pressure are the important factors affecting the dry friction characteristics.A rubber Mooney-Rivlin model was established,the friction and wear of NBR under dry friction was simulated by ABAQUS finite element method.The rule of damage to rubber caused by the changes of single factor and the shear stress under coupling condition were compared.The results show that the temperature of the contact surface increases with the speed up of the relative sliding speed,which leads to the change of rubber hardness and aggravates the wear,and the velocity has the greatest effect on the shear stress under the coupling condition.