Reservoir heterogeneities can severely affect the effectiveness of waterflooding because displacing fluids tend to flow along high-permeability paths and prematurely breakthrough at producing wells. A Proof-of-Concept (PoC) study is presented while discussing the experimental results of a research on “core-shell” technology to improve waterflooding in heterogeneous oil reservoirs. The proposed methodology consists in injecting a water dispersion of nanocapsules after the reservoir has been extensively flushed with water. The nanocapsules are made of a “core” (either polymeric or siliceous materials), protected by a “shell” that can release its content at an appropriate time, which activates through gelation or aggregation thus plugging the high permeability paths. Additional flooding with water provides recovery of bypassed oil. The initial conceptual screening of possible materials was followed by extensive batch and column lab tests. Then, 3D dynamic simulations at reservoir scale were performed to compensate for the temporary lack of pilot tests and/or field applications.