(Sep 13, 2020): The Monte Carlo method is a computational approach to calculate statistical averages for typical classical models or multi-dimensional integrals (that are averages) for quantum models. You can calculate anything that you want for a given model using the Monte Carlo method. The errors can be reduced tending to zero (for classical models). If your model is reliable, the Monte Carlo method will calculate very accurately, let's say the permeability of rock layers, for that model. Quite likely, this will correspond to the reality on the ground. But, if your starting model is inaccurate, the Monte Carlo results will still be numerically very accurate (but the results obtained will reflect the model under consideration). For such a case, these results will not correspond to the reality on the ground.

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