Technical Analysis of Sand Production for Offshore Natural Gas Hydrate Trials in South China Sea

Abstract

Natural gas hydrate emerges as a sustainable and alternative clean energy source. Japan (2013) and China (2017) have performed production trials on marine natural gas hydrate successfully. Sand production with associated risk is one of the main challenges for offshore natural gas hydrate production trials in Japan and China. Technical assessment related to sand production, transport and erosion is a crucial part for overall sand management strategy. This paper demonstrates the importance of flow assurance for marine natural gas hydrate production through the analysis of sand management in South China Sea ShenHu area. Multiphase modelling tool is used to investigate sand transport phenomenon, with parametric study focuses on the effects of production rates, particle bed height and sand particle size. Detailed analysis of particle flow and related erosion along production flow path is investigated by developing a 3-dimensional Computational Fluids Dynamics (CFD) model. Based on the matrix of sensitivity study, steady state operational map for continuous marine natural gas hydrate production is proposed. Such operational map provides useful risks level ranking based on actual field parameters including gas production rate, sand loading and particle size. The operator can maintain production at a lower risk based on the operational map. Through detailed technical analysis of sand production and transport, risks associated with sand blockage and erosion can be actively managed. This provides high values in terms of operational safety, asset integrity, and full compliance with related national or international HSSE standards.