Methods, computer programs, and information handling systems for modeling one or more reservoirs are disclosed. The method uses one or more well logs, each for a well at a location and each including one or more Relative amount of Small Size Range of the Size Spectrum of Clastic Particles (RSSRSS) values versus depth. The method includes for one or more well logs: identifying one or more facies units based on RSSRSS values, determining a thickness of one or more facies units. The method includes determining a facies type of one or more facies units, categorizing one or more facies units, and connecting one or more facies units to create a reservoir model.