Internship Report from the year 2013 in the subject Geography / Earth Science - Miscellaneous, grade: 2, 7, RWTH Aachen University (Lehrstuhl für Geologie, Geochemie und Lagerstätten des Erdöls und der Kohle), course: Petrophysics Practical Course, language: English, abstract: By inducing a gas (non-wetting fluid) into a water saturated rock, the gas will displace the water (wetting fluid), but this process just take place, when the capillary pressure is above the capillary entry pressure (gas pressure difference). First the largest pores near the sample surface are drained (drainage process). At higher capillary pressures even the smallest pores are filled with gasThe relation between capillary pressure and pore radius is given by the Washburn equation (1921), "The intrusion of a non-wetting fluid into a cylindrical capillary of radius r only occurs if the capillary pressure Pc [...] within a pore is exceeded": [...]