In some embodiments, a system, as well as a method and an article, may operate to generate map values for a plurality of parameters corresponding to respective grid blocks of a reservoir, wherein the values have been previously generated based on an initial simulation result from a model of the reservoir; to generate a sector surrogate model that includes a subset of grid blocks of the reservoir based on a criterion for identifying grid blocks that negatively affect simulation of the reservoir; to provide data inputs to execute a simulation of the reservoir using the sector surrogate model; and to generate revised data inputs, based on results of the simulation of the reservoir using the sector surrogate model, to use in a subsequent simulation using the model of the reservoir. Additional apparatus, systems, and methods are disclosed.