A fast-neutron transmission/scattering method is presented for measuri
ng the volume fraction of each of the three-phases of an oil-water-gas
how in a pipe. The gas fraction is determined by a transmission measu
rement. The relative oil-to-water content is obtained from the scatter
ing count rate by taking advantage of the salinity of water. Monte Car
lo simulations and experiments are presented to demonstrate the feasib
ility of the technique.