Study on the migration and retention behavior of sulfur-doped carbon quantum dot tracers in sandstone cores

This study innovatively synthesized yellow-green fluorescent sulfur-doped carbon quantum dots (S-CQDs) tracers and systematically investigates their transport and retention behaviors in sandstone reservoirs. By optimizing hydrothermal synthesis parameters, S-CQDs with uniform particle size and outstanding fluorescence properties were successfully prepared. Experimental evaluations demonstrated the stability of S-CQDs under extreme reservoir conditions, including high temperatures (up to150℃) and extreme pH values(3−10), as well as their interaction mechanisms with sandstone minerals. The findings indicate that S-CQDs tracers exhibit excellent transportability and long-term stability in sandstone formations, with their transport and retention behaviors governed by multiple factors, including particle size, concentration, flow rate, salinity, and clay mineral content. This study provides critical experimental data and theoretical insights for the application of CQDs as tracers in oil and gas reservoirs, highlighting their significant potential for subsurface fluid monitoring and hydrocarbon exploration.