Developing Transient Model and Simulating the Effects of Soil Properties on a Small Hole Leakage and Diffusion Characteristics in the Buried CO2 Pipelines

Abstract

Carbon dioxide (CO₂) pipelines are subject to significant risk factors of leakage, primarily due to mechanical damages, corrosion, and third-party interference. The CO₂ pipe leakage, which involves the intricate phase of the transition processes and is characterized by the pronounced fluctuations in the pressure and temperature, creates considerable challenges to the pipeline reliability and environmental safety. Therefore, a comprehensive analysis on the leakage and seepage diffusion in the buried CO₂ pipelines is essential for accurate risk assessment and decreasing the response time associated with the leak detection. This study develops a transient model to examine the small hole leakages’ behavior in the buried CO₂ pipelines. By integrating the discharge model and seepage diffusion model coupled with the thermo-fluid–solid and multiphysical fields, the study focuses on the dynamic variations in pressure, velocity, temperature, and concentration of the soil during the leakage. Additionally, this research examines the effects of soil properties, including porosity, permeability, and types with the CO₂ leakage and seepage diffusion behavior. The key indicators such as Warning Alert Time (WAT), Temperature Detection Time (TDT), and Pipeline Brittle Range (PBR) are introduced to define the hazardous boundaries, providing a systematic framework for risk assessment. The findings demonstrate that the physical properties of the soil play a crucial role in determining the leakage behavior and hazardous range of the seepage diffusion in buried CO₂ pipelines. The developed transient numerical model helps to predict the dynamic characteristics of the leakage and seepage diffusion within the soil more effectively, offering a robust theoretical foundation and technical support for assessing the consequences of the CO₂ leakage.