1. A method of interactively deriving and validating a computerized model of a hydrocarbon reservoir with downhole measurements from one or more wells in the earth, comprising: receiving data corresponding to downhole pressure measurements acquired over time at a wellbore of at least one well of interest, and corresponding flow rates from a plurality of wells including the well of interest; receiving inputs from a user identifying attributes of a hydrocarbon reservoir, the attributes comprising shapes and properties of formation regions, connections between formation regions, and locations of wells into the formation regions; operating a computer to evaluate pressure responses between each of a plurality of wells in the reservoir and the at least one well of interest in the reservoir by solving a fluid flow problem for a structure corresponding to the identified reservoir attributes; operating a computer to superpose the data corresponding to measured flow rates from the plurality of wells to the evaluated pressure responses to calculate a simulated downhole pressure at the at least one well of interest over time; comparing the simulated downhole pressure at the well of interest over time with data corresponding to the downhole pressure measurements acquired over time at the at least one well of interest; after the comparing step, receiving inputs from a user modifying the reservoir attributes, the modified attribute corresponding to at least one of a shape of a formation region or a connection between formation regions; and then repeating the operating and comparing steps for the structure corresponding to the modified reservoir attributes.