1. A method of history matching a simulation model, comprising: (a) defining regions exhibiting similar behavior in said model thereby generating said model having a plurality of regions, each of the plurality of regions exhibiting a similar behavior; (b) introducing historically known input data to said model; (c) generating output data from said model in response to said historically known input data; (d) comparing said output data from said model with a set of historically known output data; (e) adjusting said model when said output data from said model does not correspond to said set of historically known output data, the adjusting step including the step of arithmetically changing each of the regions of said model; and (f) repeating steps (b), (c), (d), and (e) until said output data from said model does correspond to said set of historically known output data.