Experimental study of relationship between capillary pressure and saturation in two-phase system in porous media

The relationship between the capillary pressure and the saturation in two phase system is the basis of gaining the relationship between the capillary pressure and the saturation in the multi-phase system. A simple and reliable setup is employed to obtain the relationship between the capillary pressure and the saturation of the water air and oil water system in the sand and soil samples. The experimental results show that,for a two-phase system with different porosity of porous media,the saturation is bigger with the reduction of porosity under the same capillary pressure;for different two phase system with same dry bulk density,the curve of capillary pressure and saturation in sand appears flater at less than a special capillary pressure value and steeper at the bigger capil ary pressure.However,the curve of the capillary pressure and the saturation in soil seems steeper than in sand. The data analysis shows that the measured values of the water-air and oil water system accord with the scaling method based on van Genutchen(1980)relation mainly proposed by Parker;and when the relationship between the capillary pressure and the saturation in one two-phase is known for a system with a specific porosity and a specific porous medium,those of other two phase can be gained by using scaling method,and the estimated value is in better agreement with the measured one.