Application of in-situ heat generation plugging removal agents in removing gas hydrate: A numerical study

• Published in: Fuel (Guildford) Vol. 323; p. 124397
• Main Authors: Wei, Na, Pei, Jun, Li, Haitao, Sun, Wantong, Xue, Jin
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2022; Elsevier BV
• Subjects: Decomposition; Electrolytes; Gas flow; Gas hydrate; Gas hydrates; Gas pipelines; Heat; Heat generation; Heating; High pressure; High temperature; Hydrates; In-situ heat generation; Inhibitors; Injection; Low temperature; Magnesium; Mass transfer; Mathematical model; Mathematical models; Natural gas; Numerical study; Phase equilibria; Plugging; Plugging removal agent; Prevention; Process parameters; Shutdowns; Thermodynamic equilibrium; Working conditions; Plugging removal agent; Gas hydrate; Decomposition; In-situ heat generation; Mathematical model; Numerical study
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2022.124397

•The in-situ heat generation plugging removal agents for gas hydrate is presented.•A new model for in-situ heat generation plugging removal agents is proposed.•Effect of in-situ heat generation system on plugging removal process is identified.•The theoretical model is in good agreement with the experimental results.•The heating temperature, alcohol and electrolyte of in-situ heat generation system are evaluated. Under the condition of low temperature and high pressure, natural gas will form solid gas hydrates in oil and gas wellbore and pipeline, resulting in blockage, pressure increase, production reduction, and even shutdown. Methods such as heat preservation, heating, and injection of inhibitors are often used in engineering to avoid the formation of hydrates. The latter, injection of inhibitors, is the most widely used means of hydrate prevention and control at present. A special inhibitor, namely an in-situ heat generation plugging removal agent, has the advantages of both heating and chemical plugging removal and is a kind of hydrate inhibitor with great potential. In this study, a new mathematical model is developed based on hydrate phase equilibrium thermodynamics and decomposition kinetics, which is used to solve the heat and mass transfer problems in the plugging removal process of the gas hydrate by using in-situ heat generation plugging removal agents. Numerical simulation is used to solve the mathematical model, and the plugging removal process and parameter variation of pure in-situ heat generation system (high/medium/low temperature), electrolyte in-situ heat generation system (containing Na+/Mg2+), and alcohol in-situ heat generation system (containing MeOH/DEG) are studied respectively. Based on the experimental results, the quantitative relationship between the plugging removal time, the dosage, and the concentration of the plugging removal agent is calculated and analyzed. Our proposed model is verified through experimental study and the calculated values of the mathematical model are in good agreement with the experimental values under different working conditions. It is concluded that the rapid removal of hydrates and the prevention of secondary formation of hydrates can be achieved by configuring the high-temperature in-situ heat generation plugging removal agents, and the efficiency of plugging removal can be enhanced by adding appropriate concentration of electrolyte and alcohol without changing the heating property of the original plugging removal agent. This study can provide theoretical guidance for the safety of oil and gas flow and the efficient development of hydrate.