On the Influence of Fine Particle Migration and Deposition on Gas Hydrate Production: Insights from the First Trial Production in the South China Sea

Abstract

Summary As a promising alternative energy source with vast reserves, the primary challenge in exploiting natural gas hydrates (NGHs) lies in achieving long-term safety and efficiency. Several production tests conducted globally have demonstrated that the production of solid particles is one of the main factors contributing to this issue. However, most studies on assessing NGH production capacity have overlooked this phenomenon and its impact on production performance, potentially compromising the accuracy of simulation results. Therefore, this study aims to quantitatively analyze the impact of fine particle migration and deposition on gas production by numerically examining the first NGH production test conducted in the Shenhu area of the South China Sea (SCS). Through comparison of simulation results with the reconstructed gas production curve, the model was calibrated and enabled an explanation of unique gas production performance during field testing. It is found that the deposition of solid particles reduced the gas production rate by nearly an order of magnitude during the initial stage of exploitation. Long-term simulation results indicate that only the three-phase layer (TPL) remains partially unobstructed and serves as the primary source of gas production in later stages. Sensitivity analysis reveals that both depressurization and particle control strategies exert significant effects on particle migration, which in turn affects gas production. Specifically, the increase in depressurization amplitude does not necessarily lead to improved gas production behavior beyond a certain threshold (approximately 6 MPa). This study illustrates the inherent trade-off between preventing particle production and increasing gas production, highlighting the need for a safe and efficient production scheme that strikes a balance between these two objectives. Based on the current study, it is preliminarily recommended to maintain a depressurization amplitude of approximately 6 MPa with a maximum depressurization rate of 3 MPa/d and ensure a fine particle filtration ratio of no less than 95%.