Nuclear magnetic resonance relaxation study of wettability of porous rocks at different magnetic fields

The wettability of the rock surface plays a very important role in the transport of fluid in porous media. The combined Amott-USBM method currently used for the determination of these values is not able to produce reliable estimates when the surface has an intermediate wettability. The nuclear magnetic resonance (NMR) technique could provide an efficient method if the parameters affected by the wettability could be established in well defined model systems. To obtain information about the effect of wettability changes upon the NMR parameters, T1 relaxation time measurements were carried out on 1H and 2H at two different magnetic fields. A large number of well defined consolidated and unconsolidated samples, with different degrees of wettability were used in this study. The results obtained showed that the T1 values, as well as the relaxation rate distribution parameters, such as the distribution width, are affected by changes in the wettability. A dependence of the T1 wettability data on the magnetic field intensity was also observed.