1. A method of estimating a wettability characteristic of a formation, comprising: disposing a magnetic resonance (MR) measurement apparatus in a borehole; generating a low gradient static magnetic field and an oscillating magnetic field in a region of the formation, the region including at least a first fluid and a second fluid; detecting a MR signal generated in the region by a receiving antenna, and calculating a T 2 distribution by a processor based on the NMR signal; calculating, by the processor, relaxation parameters for at least one fluid in the region based on an assumption that the region is a single-wet region, the relaxation parameters including a first apparent T 2 distribution corresponding to a bulk relaxation distribution of the first fluid, and a second apparent T 2 distribution corresponding to a bulk relaxation distribution of the second fluid; and estimating, by the processor, the wettability characteristic of the region based on the relaxation parameters, wherein estimating the wettability characteristic includes determining whether the region is a single-wet region or a mixed-wet region based on comparing the calculated T 2 distribution to at least one of the first apparent T 2 distribution and the second apparent T 2 distribution.