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- Title
环空条件下输气软管内的气体渗透机理.
- Authors
陆祥安; 陈家骏; 李佳彤; 温纪宏; 周 琼; 姜亮亮
- Abstract
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 results can provide technical reference for the calculation and prediction of annulus state of flexible gas line pipes, and theoretical support for the use and protection of flexible gas line pipes.
- Subjects
NATURAL gas pipelines; NATURAL gas transportation; NATURAL gas; SHIELDING gases; NATURAL gas in submerged lands; GAS condensate reservoirs; WATER-gas; POLYMERS
- Publication
Natural Gas Industry, 2023, Vol 43, Issue 8, p127
- ISSN
1000-0976
- Publication type
Article
- DOI
10.3787/j.issn.1000-0976.2023.08.012