高密度相CO2パイプラインの延性破壊制御における課題：靭性要求、不純物感度、試運転リスク

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🔬研究者:CO2パイプラインの破壊力学・熱力学モデリングにおける不純物感度と試験データ境界の研究課題を把握できる。

🏢実務担当者:CO2輸送パイプラインの設計・調達段階で靭性仕様と不純物管理、製管メーカー協議の重要性を実務に反映できる。

🏛政策担当者:CCUSインフラの安全規格・認証制度設計において実規模試験と不純物基準の整備を検討する根拠となる。

Carbon dioxide has several use cases in the oil and gas industry, such as enhanced oil recovery (EOR), carbon capture, utilization and storage (CCUS) and, more recently, transporting carbon dioxide from emitters into a shared industrial cluster or hub network. As a result, dense phase CO2 pipelines are rapidly becoming more common, with infrastructure scaling globally. Transporting dense phase CO2 through a pipeline comes with the critical design requirement to mitigate the risk of ductile fracture propagation through a fracture control plan. This paper aims to demonstrate how to design a dense phase CO2 pipeline against ductile fracture propagation, which is a high risk and uncontrollable failure event caused by the inadvertent depressurization and phase change of dense phase CO2. This necessitates identifying the charpy V-notch (CVN) energy requirements based on operating conditions and whether these toughness demands can reliably be achieved by pipe manufacturers. The approach centers around thermodynamic modeling of a given CO2 composition, which can contain several impurities that shift the phase envelope. To do this, all credible operating scenarios from a pressure and temperature perspective must identified including details related to the startup/commissioning, normal operating modes and during maintenance events such as pigging. Rapid depressurization events, such as a failure, are then thermodynamically modeled to predict the point at which the temperature and pressure cross the saturation line or saturation envelope, which is where dense phase CO2 begins to flash and undergo a phase change. During a phase change the pipeline cannot depressurize quickly enough relative to the velocity of the fracture, which allows the fracture to propagate axially along the pipeline, increasing the potential severity and damage of a rupture. The methodologies described in DNV RP-F104[1] and ISO 27913-2016[5] allow a designer to specify a CVN energy to resist this propagation, which is to be specified at the onset of pipeline design and procurement. The DNV RP F104 methodology is supported by full scale CO2 burst/propagation tests covering a limited range of pipe diameters and wall thicknesses, while the methodology in ISO 27913-2016 Annex D is based on the Battelle two-curve method. In the case of the DNV RP F104 methodology, if the subject dataset falls outside the bounds of the test data, it is recommended to complete a full scale fracture propagation test to widen the test data and determine if different diameters and wall thicknesses exhibit similar arrest-propagation behaviour as derived from the full scale test results. Impurities in the gas stream have a significant influence on the maximum saturation pressure, which directly drives the CVN energy requirement. Impurities such as nitrogen, which is commonly used in commissioning activities, can drastically influence the CVN requirement and may become challenging to achieve reliably in pipe manufacturing mills. In these cases, it is vital to have close consultation with pipe mills. Further, the DNV methodology is tightly bounded by full scale test data.

• semanticscholar https://doi.org/10.2118/235454-msfirst seen 2026-11-05 06:00:23 · last seen 2026-11-06 05:31:52