Deciphering injectivity decline in geothermal reservoirs: From formation damage mechanisms to sustainable mitigation strategies

ABSTRACT Geothermal energy is a promising renewable resource capable of providing stable, low-carbon baseload power; however, the long-term performance of geothermal reinjection systems is often constrained by injectivity decline caused by formation damage and clogging. Although individual impairment mechanisms have been widely investigated, a comprehensive understanding of the coupled physical, chemical, and biological processes controlling clogging evolution remains limited. This review examines clogging mechanisms in geothermal reinjection systems by drawing on evidence from field observations, laboratory experiments, geochemical studies, and numerical simulations. It discusses the origin, evolution, controlling factors, and mitigation strategies associated with physical clogging caused by particle invasion and fines migration, chemical clogging driven by mineral precipitation, scaling, and corrosion, and biological clogging resulting from microbial growth, biofilm formation, and biomass accumulation. Field and experimental studies show that suspended solids, silica and carbonate scaling, corrosion by-products, and microbially induced deposits can substantially reduce permeability and injectivity, particularly in near-wellbore regions. The severity of impairment is strongly influenced by fluid chemistry, temperature, pressure, particle-size distribution, flow conditions, and reservoir characteristics. Advanced monitoring technologies, geochemical modeling, filtration systems, scale inhibitors, thermal and chemical management strategies, and reservoir-specific operational optimization have shown potential for mitigating clogging-related damage. Nevertheless, a comprehensive review examining physical, chemical, and biological clogging mechanisms collectively in geothermal reinjection systems remains lacking, limiting the development of predictive and sustainable mitigation strategies. By consolidating current knowledge, this review provides a mechanistic basis for improving injectivity prediction and supporting the long-term sustainability of geothermal reinjection operations.