In the Minami Kuwayama oil field located onshore in Japan, asphaltene deposition problems have been identified not only in the surface facility but also in the reservoir during production. In this study, to understand the mechanism of productivity deterioration due to asphaltene deposition, a numerical simulation study was conducted. An equation of state (EOS) based fluid model was incorporated into a compositional flow simulator, capable of predicting asphaltene deposition behavior in the reservoir. History matching was conducted for the actual production history showing a drastic decline within 6 months. Using the history matched model, several numerical investigations were conducted on the asphaltene deposition damage and productivity enhancement by hydraulic fracturing to provide a guide line for the fracturing design.