Evaluation of Flow Assurance and Hydrate Control in Subsea Natural Gas Production

Abstract

With the advancement of science and technology, the importance of oil and gas resources in promoting global economic and social progress is increasing. However, one of the most significant technological challenges facing the industry today is securing the production flow in deep water exploration. Offshore production, particularly in deep water, presents unique challenges due to extreme water depths and harsh marine environments, including high pressures and low temperatures. Production risers, connecting wells to Floating Production Storage and Offloading vessels (FPSOs), face operational challenges such as hydrate formation, scale formation, asphaltenes, corrosion, and slugging. a natural gas stream from the Niger Delta, transported via pipeline, was chosen for analysis. The temperature and pressure profiles along this pipeline were used as inputs for hydrate formation assessment. The primary aim of this study is to delve into the flow assurance aspects of natural gas produced from a subsea environment.

This research was devoted to hydrate control in subsea natural gas production using results from water concentration estimation for reservoir, wellhead and onshore receiving terminal conditions. For illustration, a natural gas stream from the Niger Delta was selected where the transportation medium is a pipeline. Further implementation as part of the hydrate formation assessment input was done on the temperature and pressure profile along this pipeline.

A hydrate inhibition strategy based on monoethylene glycol (MEG) is under consideration. The use of MEG is well-established and qualifies as a proven technology for hydrate control in subsea environments. It is revealed that in the case if a temperature falls below 20°C and pressure increases above 100 bar, conditions conducive to hydrate formation are met. Estimation of water concentration thus suffices to give useful information as possible prevention methods to hydrate formation gas flows through the pipeline. The actual thermodynamic conditions required for the hydrate formation can also be deduced from the temperature and pressure data. Operations-based controls, such as adjusting volume-flow rates, can be instrumental in preventing the conditions conducive to hydrate formation.