Numerical Simulation of Slotted Screen Plugging Mechanism Based on Cfd-Dem Coupling

As the simplest and commonly used mechanical sand control method in well completion, slotted screen sand control is used for filling sand control, independent sand control in thermal production wells or geothermal wells. In order to explore the plugging mechanism of slotted screen and the factors affecting sand production during sand control, the CFD-DEM coupling method is used in this paper. The discrete element method is used to establish the model considering the physical properties of sand particles in the formation, and the fluid flow model is established combined with the finite volume method, and the full coupling solution of the two is realized and the model verification is completed. The effects of particle size distribution, sand concentration, slotted size and fluid velocity on slotted screen plugging are studied, and the plugging mechanism of slotted screen is revealed. The following research results are obtained. First, the retention form of sand particles at the screen gap is the fundamental factor affecting screen plugging. Sand bridging will have a certain probability of collapse, resulting in “false stability”. Second, the proportion of larger diameter sand determines the formation time and stability of “sand bridge”, and the proportion of smaller diameter sand determines the compactness of solid retention. Third, sand concentration is very important to control the plugging removal frequency of screen. Fourth, the gap size and fluid velocity affect the pressure difference on the screen surface and the stability of the “sand bridge”. This study provides a reference for optimizing the selection and production control of slotted screen during the downhole sand control design.