Mini-Review on In-Situ Performing Reactive Nanomaterials: Enhancing Oil Recovery in Harsh Reservoirs

Enhanced oil recovery (EOR) is critical for maximizing hydrocarbon extraction from reservoirs, especially in high-temperature and high-salinity (HTHS) environments where conventional techniques face stability challenges. In-situ performing reactive nanomaterials enable EOR (8–35% average recovery enhancement for single-component systems) via reservoir reactions (growth, catalysis) altering crude oil properties in HTHS (≥120 °C, ≥2 × 104 mg/L) environments. Furthermore, optimized multimaterial combinations further boost enhancement to over 45%. This review covers their types (water plugging, interfacial regulation, catalytic viscosity reduction, multifunctional), key factors (temperature, salinity), mechanisms, and harsh reservoir applications, introduces their in situ experimental characterization methods, and presents field application cases and environmental impact assessments. It highlights the shift to antithermal/salt composite structures and multimechanism synergy for efficient displacement in heterogeneous harsh reservoirs. Integrating latest advances (in situ characterization) and challenges (HTHS stability, high precursor costs), it analyzes material design and industrial application bottlenecks and proposes targeted future development directions, outlining their potential, limitations, and complex reservoir significance.