A computer-based method of conditioning reservoir model data includes performing a modeling process within a 3D stratigraphic grid to generate an initial model including one or more facies objects within the model volume, the modeling process including parametric distributions, initial and boundary conditions as well as depositional and erosional events to define the facies objects within the model volume. The mismatch between this initial model and the conditioning well data and potential input trend model is applied to compute a locally variable constraint model. The method further includes executing a multiple point statistics simulation with this constraint model that varies between completely constrained by the initial model at locations where the initial model is consistent with known well data and potential input trend models, and unconstrained by the initial model at locations where the initial model does not match known well data or potential input trend models to allow conformance to the known data.