Systems and methods are disclosed for generating a set of facies realizations. A computer-implemented method may use a computer system that includes a physical computer processor and data storage. The computer-implemented method may include: obtaining a geobody index, obtaining facies probability vectors for the multiple geobodies, assigning facies to the multiple geobodies based on the facies probability vectors, obtaining a target facies proportion for the subsurface volume of interest, reassigning a first geobody having a first facies based on a first facies probability vector of the first geobody, and reassigning remaining ones of the multiple geobodies with different facies.