埋地CO2管道泄漏扩散特征研究进展

1.中石化石油工程设计有限公司·中国石化碳捕集、利用与封存(CCUS)重点实验室;2.国家管网集团科学技术研究总院分公司;3.中石化石油工程建设有限公司

埋地管道;CO2;泄漏扩散;土壤;数值模拟

Research progress on characteristics of leakage and diffusion of buried CO2 pipeline
ZHANG Junpeng1,MIAO Qing2,JING Shaodong1,WANG Yongsheng3,OUYANG Xin2,FAN Zhenning1,LIANG Haining1,ZHANG Jian1

1.Sinopec Petroleum Engineering Corporation//Sinopec Key Laboratory for Carbon Capture, Utilization and Storage; 2.PipeChina Institute of Science and Technology; 3.SINOPEC Petroleum Engineering & Construction Corporation

buried pipeline, CO2, leakage and diffusion, soil, numerical simulation

DOI: 10.6047/j.issn.1000-8241.2024.05.003

备注

【目的】CO2管道输送是碳捕集、利用与封存(Carbon Capture, Utilization and Storage, CCUS)技术产业链中的关键环节,其在运行过程中存在意外泄漏风险。相比于地上管道,受土壤阻力的影响,埋地高压管道的泄漏扩散机制更加复杂。然而,目前对于CO2管道泄漏扩散特征的研究综述主要聚焦于地上管道泄漏的场景。【方法】针对埋地管道小孔泄漏与全尺寸断裂两种常见场景,基于文献调研对目前埋地管道泄漏扩散的实验与模拟研究现状进行梳理评述,探究了土壤地质条件、土壤温度、外界压力以及外界风速对CO2气体土壤渗流扩散过程中的影响,并总结了当前模拟埋地CO2管道全断裂泄漏扩散的建模方式与物理模型。【结果】对于埋地CO2管道小孔泄漏近场泄漏源特征,主要以开展小型实验的方式研究泄漏口附近土壤温度变化以及干冰层、冻土层的增长规律。对于埋地CO2管道小孔泄漏远场扩散特征的模拟研究,大多假设土壤孔隙度不发生变化,并未考虑流体相变与冲击压力对土壤孔隙度的影响。埋地管道全尺寸断裂条件下气体射流扩散的研究主要以模拟为主,且大多数模型直接以形成的洞坑为物理原型,未考虑洞坑形成对气体射流扩散的影响。【结论】埋地CO2管道全尺寸断裂的现场测试和小孔泄漏扩散理论模型建立仍有很大发展空间,建议通过专项攻关完善地质条件和外界环境影响下CO2气体在土壤中的扩散机制,加大投入开展埋地CO2管道大孔径或者全尺寸断裂泄漏扩散试验,获取更多实验数据,以建立更加全面准确的数学物理模型。(图3表2,参[56]
[Objective] CO2 pipeline transmission, a key link in the industrial chain of carbon capture, utilization, and storage (CCUS) technology, is exposed to risks of accidental leakage during operation. Compared with aboveground pipelines, buried high-pressure pipelines follow the leakage and diffusion mechanism subject to more intricate impacts from soil resistance. Unfortunately, existing researches center on reviewing the leakage and diffusion characteristics of aboveground CO2 pipelines, neglecting the specific challenges faced by buried ones. [Methods] This study focused on two common scenarios involving buried pipelines: small hole leakage and full-scale fracture. The experimental and simulation research progress on leakage and diffusion of buried pipelines was reviewed and evaluated through literature research. The influences of soil geological conditions, soil temperatures, ambient pressures, and wind velocities on the CO2 seepage and diffusion processes in the soil were also examined. Furthermore, the study summarized the currently prevalent modeling methods and physical models utilized for exploring leakage and diffusion of buried CO2 pipelines with full-scale fractures. [Results] The soil temperature changes near leakage openings and the growth patterns of dry ice layers and frozen soil layers were studied mainly through mini experiments, to reveal the characteristics of near-field leakage sources in the small hole leakage scenario of buried CO2 pipelines. The simulation study of far-field diffusion characteristics in the same scenario was mostly based on the assumption of constant soil porosity, neglecting the effects of phase transition of fluid and shock pressure on soil porosity. The gas jet diffusion of buried pipelines in the full-scale fracture scenario was studied mainly through simulations, and most models were directly derived from the physical prototype of formed pits, without considering the effects of pit formation on gas jet diffusion. [Conclusion] There remains considerable room for advancement in conducting field tests for full-scale fractures of buried CO2 pipelines and developing theoretical models for small hole leakage and diffusion scenarios. It is recommended to conduct specialized research on the diffusion mechanism of CO2 in soil, emphasizing geological conditions and ambient environmental factors. Furthermore, efforts should be intensified in conducting leakage and diffusion experiments for buried CO2 pipelines with large diameters or full-scale fractures, aiming to acquire more experimental data essential for constructing comprehensive and precise mathematical and physical models. (3 Figures, 2 Tables, 56 References)
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