Abstract: In order to study the absorption mechanism of liquids in oil reserviorcore, several samples were prepared using the same rock core :1)different quantities of kerosene adsorbed ;2) different quantities of water adsorbed ;3)some quantity of waker was adsorbed first and then some quantity of kerosene was adsorbed later.The NMR spin-lattice relaxation times were determined for the above three groups of samples;The conclusion is that the closer the water and oil molecules to the solid surface the shorter the relaxation time is.According to the conclusions on petroleum geology and NMR study results a NMR model of two-phase (oil/water) system in porous sandstone was proposed.

Key words: NMR, Spin-lattice, Relaxation time, Porosity