Reyhaneh Pouryousef

A gas hydrate is a crystal structure formed of cage-like hydrogen bonds between water molecules and trapping guest gas molecules in the hydrate cage at low-temperature and high-pressure thermodynamic conditions. By clogging pipes, valves, and other oil and gas refining and transmission equipment, natural gas hydrate causes pressure drop and flow reduction, ultimately leading to pipeline explosion and causing financial and life risks. So far, physical and chemical methods have been used to prevent this problem. Physical methods such as pipeline insulation, depressurization, dehumidification, and heating are not technically and economically desirable.  Therefore, chemical methods are considered as an alternative approach. Chemical methods refer to inhibitors, which include Thermodynamic Hydrate Inhibitors (THIs) and Low-Dosage Hydrate Inhibitors (LDHIs). Low-Dosage Hydrate Inhibitors are divided into Kinetic Hydrate Inhibitors (KHIs) and Anti-Agglomerates (AAs). Thermodynamic Inhibitors are not economically and environmentally acceptable, due to the required high-weight percentages to be effective. Anti-Agglomerates are unacceptable due to their reaction with other additives, such as corrosion inhibitors, and their effectiveness after hydrate formation. However, Kinetic Inhibitors are a suitable option due to their low dosage and delaying hydrate formation reaction. In this study, the Iron Oxide (Fe3O4) nanoparticles were functionalized with polyvinyl pyrrolidone (PVP) polymer (Fe3O4@PVP) as a Kinetic Inhibitor using the Co-precipitation method and characterized by PXRD, FESEM/EDX, and TGA analyses. Then, a PVT test in a high-pressure cell was used to investigate Fe3O4@PVP inhibitory effect. In this method, the time of hydrate formation is obtained by detecting the pressure stabilization point when temperature decreases at a constant volume. The same steps are repeated for PVP, and the Fe3O4 effect on this material's inhibition is determined by comparing the PVT graphs. The reusability of Fe3O4@PVP is determined by creating a magnetic field; the nanostructure is separated and dried at 100°C. Finally, the recycled nanostructure is added to the system, and its inhibition is measured by PVT testing and compared with previous graphs. Fe3O4@PVP with a large surface area is expected to reduce the weight percentage of the kinetic inhibitor required and increase the performance due to the increased contact surface of PVP with water molecules in the gas flow line. ‌In addition, Fe3O4@PVP is easily separated with a strong magnet due to the magnetic nature of its core, which makes it possible to reuse as an inhibitor.  This chemical inhibitor's recyclability and small quantities required make it an environmentally friendly and economical inhibitor. 

Co-author/s:

Ali Safaei, Assistant Professor, University of Tehran.

Azadeh Ebrahimian Pirbazari, Associate Professor, College of Engineering, University of Tehran.

Dr. Behnam Shahsavani, Assistant Professor, Petroleum Engineering Department, School of Chemical and Petroleum Engineering, Shiraz University.