2021 Volume 77 Issue 2 Pages 185-194
Pressure equations and hybrid equations could been derived from Richards equation and have been frequently employed for investigation and study of seepage flow and multiphase flow. Variables of pressure equations and hybrid equations are gas and water pressures and water pressure and water saturation, respectively. On the other hand, saturation equations in which a variable is only water saturation had been rarely used in the investigation and study. However Klute saturation equation and Peaceman saturation equation are explained in some books and articles. This paper organized the derivation of the Klute saturation equation and Peaceman saturation equation and compared the two saturation equations. Furthermore in this paper distributions of water saturation obtained by numerical simulations with Klute saturation equation and Peaceman saturation equation were compared with that calculated from capillary pressure which equals difference between hydrostatic pressure and static gas pressure. As a result, the distribution of water saturation obtained by Peaceman differed from that obtained from Klute saturation equation and was more accurate than Klute saturation equation.
