Fouling Mechanisms in Produced Water Reinjection: Insights into Near-Wellbore Damage from a Micromodel Study

Produced water treatment poses significant environmental and engineering challenges. Reinjection into subsurface reservoirs is a sustainable disposal method that minimizes discharges to the sea. However, the injectivity decline near the wellbore remains an persistent issue. In this study, mixtures of seawater and produced water are injected into glass micromodels at 70 °C to simulate reinjection into porous media and directly visualize near-wellbore damage mechanisms. Combined permeability measurements and high-resolution imaging identified three dominant contributors to injectivity loss: microbial biofilm growth, cyclic precipitation and redissolution of inorganic solids with diverse morphologies, and gas bubble entrapment. While gas formation is unlikely under reservoir pressure, the observed biofouling and mineral scaling processes provide new insights into the fouling phenomena in terms of visualization of biofilm formation and different morphologies of precipitates. The developed methodology can advance the understanding of near-wellbore damage and offer practical input for developing improved microbial control and scaling prevention strategies to sustain injectivity and reduce the environmental risks of water disposal.