Research and Application of Circulating Filling Sand Control Technology for Geothermal Wells

The geothermal wells in Nanpi County extract from the Neogene Guantao Formation, characterized by unconsolidated sandstone with high porosity and permeability interbedded with mudstone sequences, where predictive methods confirm high sand production risks. Sand influx threatens operational integrity by reducing or halting production while accelerating erosion of surface and downhole equipment, causing casing damage and potentially leading to well abandonment, which necessitates robust pre-production sand control. Conventional manual gravel packing combined with sand screens, though generally effective, fails in wells exceeding 10° inclination due to premature gravel settling in deviated sections that prevents targeted placement. To overcome this limitation, this paper introduces a circulating gravel-packing technique where surface pumps inject gravel-laden fluid into the tubing-casing annulus, transporting gravel to the bottomhole target zone. At this location the gravel settles as the carrier fluid enters the completion string through the sand screen and returns to surface. This innovation effectively prevents sand bridging and ensures complete production-interval filling in high-angle wells exceeding 10 degrees, delivering a reliable sand control solution for geothermal reservoirs.