A probability functional method is used to determine the most probable state of a reservoir or other subsurface features. The method is generalized to arrive at a self-consistent accounting of the multiple spatial scales involved by unifying information and homogenization theories. It is known that to take full advantage of the approach (e.g. to predict the spatial distribution of permeability, porosity, multi-phase flow parameters, stress, fracturing) one must embed multiple reaction, transport, mechanical (RTM) process simulators in the computation. A numerical technique is introduced to directly solve the inverse problem for the most probable distribution of reservoir state variables. The method is applied to several two and three dimensional reservoir delineation problems.