摘要
将微观泄漏机理引入非API套管接头密封性能研究,旨在建立表面粗糙度和密封结构加工参数与微观气体泄漏率之间的函数映射关系。通过Monte Carlo随机正态分布抽样公式结合密封表面粗糙度加工参数,模拟得到服从正态分布和预设表面粗糙度值的粗糙表面轮廓曲线,依据不同样本容量和表面粗糙度下平均峰角、平均峰高和三角峰数目/样本容量等轮廓曲线形貌特征统计数据,分析得到模拟曲线几何共性特征。结合弹塑性力学接触理论和计算得到的粗糙表面几何形貌参数,建立具有几何共性特征的高硬度管体层锥体压入低硬度软金属镀层平面简化泄漏模型,将气体泄漏看作不可压缩稳定层流,推导出含有密封面微观几何形貌特征(平均峰角和平均峰高)的气泄漏率计算公式。将与套管接头主密封结构重要加工参数相关的总密封预紧压力代入微观气体泄漏率计算公式,得到适用于非API套管接头密封性能定量评估计算方法。泄漏率实例计算结果表明,不同表面粗糙度对应气体泄漏率相差一个数量级,且加工精度等级越高相差越明显。非API套管接头密封设计和性能评估必须考虑金属机加工表面粗糙度。
The micro-leakage mechanism was introduced into an evaluation for sealing performance of non-API casing connections, in order to establish the function mapping relationship of surface roughness, sealing structure processing parameters, and gas leakage rate. Rough surface contour curves with normal distribution and preset surface roughness were simulated using the Monte Carlo normal distribution random sampling formula combined with surface roughness processing parameters of the sealing surface. Micro-geometric common feature of the simulated contour curves were analyzed according to their morphological statistical data including average peak angle, average peak height, and the ratio of peak number to sample size associated with different sample sizes and surface roughness. Second, a simplified leakage model of high-hardness tube cone pressed into low-hardness soft metal coating surface with micro-geometric common feature was built, using a combination of rough surface micro-geometric parameters and the elastic-plastic contact mechanic theory. A calculation formula of gas leakage rate containing micro-geometric common feature parameters (e. g. , average peak angle and height) was deduced by assuming gas leakage as an incompressible steady laminar flow. Finally, a quantitative evaluation method for sealing performance of non-API casing connections was obtained by substituting total sealing preloaded pressure (which is relevant to important processing parameters of the sealing structure of casing connections) into the calculation formula of gas leakage rate. The calculation results show that the gas leak rates corresponding to varying surface roughness differ by one order of magnitude. The higher the machining accuracy is, the greater the difference is. Thus, surface roughness of metal machining is an important factor that needs to be considered in the design and performance evaluation for sealing structure of non-API casing connections.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2014年第5期963-971,共9页
Acta Petrolei Sinica
基金
国家自然科学基金青年科学基金项目(No.51105381
No.51205412
No.51204203)
山东省优秀中青年科学家科研奖励基金项目(BS2012ZZ012)
中国石油天然气集团公司重点实验室基础研究课题(2011A-4208)
中央高校基本科研业务费专项资金项目(l4CX02075A)资助
关键词
套管接头
密封性能
泄漏率
表面粗糙度
非API
密封结构
加工精度
casing connection
sealing performance
leakage rate
surface roughness
non-API
sealing structure
machining precision