However, the rock sample exhibited fast surface RELAXATION (shorter T2 times) after each diluted slug of seawater, mainly twice diluted, 10 times diluted, and also 20 times diluted seawater.

The nuclear magnetic resonance longitudinal relaxation time, T1 , of fluids in porous sedimentary rocks is dominated by relaxation at the pore-grain interface.

Under certain conditions the transverse relaxation time, T2, is also controlled by surface interactions.

The T1/T2 ratio and the frequency dependence of T1 can be important constraints on theories of the relaxation mechanism. These quantities are reported for a variety of porous sandstone and carbonate rocks. The broad distributions of relaxation times that characterize these materials are explicitly taken into account.

итого:
relaxation - релаксация
T2 - время поперечной релаксации