Abstract: A two-phase fluid, flow having a first fluid and an immiscible second fluid, is passed through a core sample. The core sample is scanned with X-rays to produce a display of fluid distribution within the core sample. Electrical resistivity is measured along the length of the core sample for those intervals having uniform first fluid distribution. The two-phase flow is continued to repetitively decrease the first fluid saturation in a plurality of drainage cycles with electrical resistivity being again measured for each drainage cycle. Thereafter, the two-phase fluid flow is continued to repetitively increase the first fluid saturation in a plurality of imbibition cycles with electrical resistivity being again measured for each imbibition cycle.