3D CFD-DEM modeling of sand production and reservoir compaction in gas hydrate-bearing sediments with gravel packing well completion

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Sand production is one of the bottlenecks restricting the safe, efficient, and controllable production of hydrates. Enhancing the understanding of mesoscopic sand production responses is essential for sand production risk management. Yet, existing mesoscopic sand production models inadequately capture the effects of hydrate cementation, resulting in an incomplete assessment of the mechanical impacts of hydrates on sand production. Herein, we developed a new three-dimensional model for sand production in gas hydrate-bearing sediments (GHBSs) with gravel packing well completion, utilizing the coupled computational fluid dynamics and discrete element method (CFD-DEM). The model considers the coupled interactions of mechanical weakening and permeability variation in GHBSs caused by hydrate cementation reduction. Simulations are analyzed to clarify the responses of sand production and reservoir compaction under the coupled mechanical, hydraulic, and sand control completion in GHBSs during depressurization. The high fluid flow rate induced by a high production pressure differential can promote sand production and reservoir compaction. Additionally, the high effective stress and high hydrate dissociation rate induced by a high production pressure differential are beneficial for initial sand production, but they can also prematurely lead to gravel packing layer obstruction, inhibiting the final sand production. This also results in a dual impact on compaction deformation, enhancing it through compaction while decelerating it by inhibiting sand production. This work provides a viable simulation idea and preliminary insights into the mechanism of sand production from GHBSs.