New strategy for enhancing reinjection of geothermal tailwater in sandstone reservoirs using an electric field

• Electric field is shown to enhance reinjection in laboratory core samples. • The reinjection behavior of geothermal tailwater under electric field influence is systematically investigated. • Electric field effects on reservoir physical parameters and pore structure are quantitatively analyzed. • A conceptual approach is proposed based on laboratory observations using electric field technology. The effective exploitation of geothermal sandstone reservoirs can help meet growing energy demands and contribute to carbon neutrality. Reinjection of geothermal tailwater is essential for sustainable geothermal development but is often limited by low reinjection efficiency. In this study, the applicability of electric field technology to improve tailwater reinjection in geothermal sandstone reservoirs was investigated through laboratory core flooding and nuclear magnetic resonance (NMR) experiments. The results show that an optimized electric field strength of 1 V/cm increased reinjection efficiency by 2.5 times compared to untreated samples. Bubbles generated under the electric field increased formation pressure from 0.02 MPa to 0.23 MPa, aiding energy recovery. Furthermore, the electric field improved permeability and porosity by increasing both the number and size of pores, thereby enhancing reservoir properties and reinjection performance. These findings demonstrate that electric field technology demonstrates the potential to improve tailwater reinjection under laboratory conditions and warrants further investigation at larger scales to assess its practical feasibility.