Various implementations directed to determining a phase behavior of a reservoir fluid are provided. In one implementation, a method may include receiving a plurality of predetermined pore size data, a plurality of predetermined bulk fluid data, and a plurality of predetermined kerogen data that are based on historical data for a plurality of hydrocarbon reservoirs. The method may also include creating a library of a plurality of simulated phase behavior data for the predetermined pore size data, the predetermined bulk fluid data, and the predetermined kerogen data. The method may further include determining a phase behavior of a reservoir fluid disposed in an actual hydrocarbon reservoir using the library.