Experimental study and evaluation analysis on the plugging mechanism of sand control screen in argillaceous Fine-Silt gas hydrate reservoirs

The argillaceous fine-silt gas hydrate reservoirs, characterized by high clay content(20-25%) and the median sand grain size(10-15 μm), pose extreme challenges to sand control. Based on analyses of existing sand production laws and plugging mechanisms, the paper focuses on the characteristics of argillaceous fine-silt reservoirs and systematically reviews conventional sand control methods and the small-scale simulation devices. An innovative full-scale experimental evaluation device was developed, enabling simulation of sand control screens performance under different well deviation angles, and the dynamic down-hole conditions, and a corresponding plugging test and evaluation method was established. The experimental investigations via the device revealed the plugging characteristics of sand control screens in the target reservoirs: sand-mudstone interbedding induces clay hydration and swelling, driving fine particles into the screen's sand retention layer; coupled with the layer's irregular, heterogeneous pores, this hinders particle expulsion and drastically reduces screen permeability. Further, the study clarified the influence laws and sensitivity of four key factors( clay content, mineral composition, well inclination angle, and production rate) on sand screen performance. The dominant factors were identified as clay content and production rate: screen permeability dropped sharply when clay content reached 55%, and declined fluctuatingly with increasing production rate (40-160 L/min) until stabilizing beyond a critical threshold. The non-dominant factors included mineral composition and well inclination angle: montmorillonite content exceeding 45% exacerbated plugging (synergistically amplified by production rate), while screen permeability decreased moderately from 426 mD (0°, vertical well) to 300 mD (90°, horizontal well), with well inclination angle exerting insignificant sensitivity on plugging. These findings hold critical guidance for sand control in argillaceous fine-silt hydrate reservoirs. It is necessary to maintain a dynamic balance between the effective sand control and optimal productivity release.