Capillary pressure and relative permeability are the key parameters that govern fluid flow in the reservoirs. Relative permeability data are used to predict the most effective hydrocarbon displacement mechanisms in a reservoir and how to get the most of the oil or gas out of the reservoir as quickly and cheaply as possible. Determination of capillary pressure and relative permeability are traditionally conducted in the laboratory. However it is expensive, difficult, and time-consuming to measure capillary pressure and relative permeability in many cases. The models representing such relationships show that capillary pressure and relative permeability could be inferred from resistivity data using the analytical mathematical models derived theoretically. In fact the other two could be inferred using these models if one of the three parameters (capillary pressure, relative permeability, and resistivity) is known. In this paper, Laboratory measurements of resistivity index, capillary pressure with different techniques, and relative permeability  were conducted on the samples from two fields representing  Libyan sandstone and carbonate  reservoirs  in order to review analytical mathematical models correlating resistivity index , capillary pressure, and relative permeability.  The results of relative permeability calculated using these models are analyzed and compared with experimental data which obtained in the lab.

This paper shown the three flow distribution functions, resistivity index, capillary pressure and relative permeability. These functions are coupled and can be inferred from each other using the mathematical models if one of the three parameters is known, and Relative permeability can be calculated from the experimental data of both resistivity index and capillary pressure. Good matching between relative permeabilities calculated from models and with experimental data .