摘要
针对特殊螺纹实现高气密封能力的问题,基于密封接触应力分布及其变化规律建立了锥面对锥面主密封过盈接触应力以及井下载荷工况下扭矩台肩面实际接触应力计算模型,并且基于密封接触能机理和密封面极限屈服条件建立了特殊螺纹气密封性能定性评价方法。以锥面对锥面主密封为例,对比分析了7种井下载荷工况对密封面平均接触应力、密封接触长度以及主密封面和台肩面的密封性能影响规律,绘制了防泄漏安全系数为1.0、1.5和2.0时锥面对锥面密封结构的密封包络线。结果表明:轴向拉伸载荷和环空外压会降低主密封结构和台肩面密封性能,轴向压缩载荷和油管温度升高有利于提高主密封结构和台肩面密封性能,而气体内压对主密封面接触应力有自增强效应,但会降低台肩面接触应力;控制合理环空内压以及上扣时台肩面作用扭矩有利于减小井下载荷工况对油管特殊螺纹密封性能的影响;绘制的密封包络线可以方便地设计锥面对锥面密封结构参数。
With view to high pressure gas sealing performance of premium thread,a calculation model of interference constant stress of primary sealing structure for conical surface to conical surface and the actual constant stress of torque shoulder surface under downhole loads was established based on the distribution of sealing constant stress and its variation law. A qualitative evaluation method of gas sealing performance of premium thread on the basis of sealing contact mechanism and the sealing surface ultimate yield condition was proposed. One case study was conducted on conical surface to conical surface of primary sealing. The influences of 7 kinds of downhole loads on the average constant stress of sealing structure,sealing contact length and primary sealing surface and shoulder surface were comparatively analyzed.And the performance of the sealing envelope curves of the conical surface to conical surface while the leakage prevention safety factor is 1.0,1. 5 and 2. 0 were drawn. It is shown that both the axial tensile load and annulus pressure would reduce the sealing performance of primary sealing structure and shoulder surface; the axial compression load and tubing rising temperature are beneficial to improve the sealing performance of primary sealing structure and shoulder surface,however,the internal pressure of gas have self-enhancement effects on contact stress of primary sealing surface will reduce the shoulder surface contact stress. The reasonable annulus pressure and torque of shoulder surface during screwing can improve the sealing performance of premium thread of tubing. The sealing envelop curve is convenient to design the parameters of conical surface to conical surface.
出处
《石油管材与仪器》
2016年第4期25-29,34,共6页
Petroleum Tubular Goods & Instruments
基金
四川省杰出青年基金项目"页岩气水平井套管完整性研究"(项目编号:2016JQ0010)
关键词
特殊螺纹
气密封
锥面对锥面
接触应力
主密封参数
评价
premium thread
gas seal
conical surface to conical surface
contact stress
primary sealing parameters
evaluation
