Method and apparatus are provided to determine the distribution of fluids in a sample employing a centrifuge. The apparatus is an automated centrifuge which may employ a plurality of X-ray energies to determine a two-dimensional image of the saturation of multiple fluids in a sample. The saturation images may be used to calculate a capillary pressure curve or relative permeability curve for a borehole core sample. The X-ray source may be selectively synchronized with at least one of the rotating specimen holders to allow for preselection of which specimen holder is to be imaged by the X-ray energies. The method images a sample in a plurality of points during centrifuging to determine fluid distributions in the sample. Alternative automated centrifuges are provided which may also measure resistivity during centrifuging and may have the source and detector located on the sample holder.