环空条件下输气软管内的气体渗透机理  

Gas permeation mechanism in the annulus of flexible gas line pipes

作　　者：陆祥安 陈家骏 李佳彤 温纪宏 周琼[2] 姜亮亮[3] LU Xiang'an;CHEN Jiajun;LI Jiatong;WEN Jihong;ZHOU Qiong;JIANG Liangliang(Guangling College,Yangzhou University,Yangzhou,Jiangsu 225000,China;China University of Petroleum-Beijing,Beijing 100083,China;University of Calgary,2500 University Drive NW,Calgary,Alberta T2N 1N4,Canada)

机构地区：[1]扬州大学广陵学院 [2]中国石油大学(北京) [3]卡尔加里大学

出　　处：《天然气工业》2023年第8期127-134,共8页Natural Gas Industry

基　　金：扬州大学广陵学院自然科学研究项目“麦秸秆纤维热塑复合材料机械性能预测模型研究”(编号:ZKZD18004);江苏省高等学校自然科学研究面上项目“生物质短纤维复合材料开发与制备”(编号:20KJD430006)。

摘　　要：输气软管有着非固定管线的优势被大量用于海上天然气的输送,是海上油气高效开发的重要设备之一,但由于天然气中小分子组分在压力作用下溶解到软管高分子内衬层中,会进一步扩散到软管环空层中,在环空条件将影响气体的渗透行为,会导致环空憋压并产生酸性环境威胁软管结构和使用寿命。为此,采用物理模拟与数值模拟结合的方法,研究了温度、压力、金属遮挡和泄压等条件下研究了环空输气管内部气体扩散过程,并分析了对气体渗透的影响。研究结果表明:(1)环空中的金属抗压层与高分子材料贴合,对气体的渗透起到了遮挡作用;(2)理论模型中利用第3类边界条件引入遮挡系数表征其遮挡作用,为理论计算的简化处理起到积极作用;(3)环空中的温度和压力影响水组分的相态变化,当环空中水组分的气体密度达到临界值,会出现液化水,液化水的出现为环空酸性条件提供了物质基础;(4)环空压力是影响渗透速度的另一个主要因素,对于新管,环空中压力上升的变化率随环空压力先增加后降低,对于输气过程中的软管,环空泄压后,其压力上升的变化率初始较大,随环空压力升高而降低。结论认为,实验和模拟过程得出的结论,可为输气软管环空状态计算与预测提供技术参考,也为输气软管的使用和保护提供了理论支撑。Flexible gas line pipes have been extensively used for offshore natural gas transportation due to their characteristics of nonfixed line pipes,and it is one of the important equipment for the efficient development of offshore oil and gas.Under the action of pressure,however,the small molecular components of natural gas dissolves into the polymer liner of flexible pipes and then diffuses into the annulus of flexible pipes,which will influence the permeation behaviors of gas in the annulus,resulting in annulus pressure building and acidic environment,so the structure and service life of the flexible line pipes are threatened.By virtue of the combined method of physical simulation of numerical simulation,the gas diffusion process inside the pipe annulus under the conditions of temperature,pressure,metal shielding and pressure relief is studied,and the effect on gas permeation is analyzed.The following research results are obtained.First,the metal compressive layer in the annulus is fitted with the polymer material to shield gas permeation.Second,the shielding coefficient is introduced into the theoretical model by using the third type of boundary conditions to characterize the shielding effect,which plays an active role in simplifying the theoretical calculation.Third,annulus temperature and pressure influence the phase change of water components.When the gas density of the water components in the annulus reaches the critical value,condensate water will appear.The appearance of condensate water provides the material base for the acidic conditions in the annulus.Fourth,annular pressure is another important factor affecting the permeation rate.For a new pipe,the change rate of annulus pressure rise increases first and then decreases with the annulus pressure,while for the flexible line pipes in the process of gas transportation,the change rate of pressure rise after the annulus pressure relief is initially large and then decreases with the increase of annulus pressure.In conclusion,the experimental and simulation resu

关 键 词：海上 油气开发 输气软管 气体渗透 传质传热模型 环空 温度 压力 

分 类 号：TE973.92[石油与天然气工程—石油机械设备]