A 3D facies model generator system and methods thereof include a processor and repository comprising (i) facies data, (ii) sequence stratigraphy, and (iii) a depositional model for a subject reservoir. The processor is operable to generate a 3D stratigraphic sequence framework comprising a plurality of facies based on received facies data and sequence stratigraphy, generate a facies volume fraction for each facies, compare each facies volume fraction with the depositional model for the subject reservoir, reassign the facies volume fraction for the facies of the plurality of facies to another facies of the plurality of facies when the comparison determines that the facies of the 3D stratigraphic sequence framework is incorrectly assigned, generate a plurality of 3D probability trends for the plurality of facies based on the facies volume fraction for the respective facies, and generate the 3D facies model based on the 3D probability trends.