(n.) Formation Evaluation. A type of nuclear magnetic resonance (NMR) log that is designed to record properly only the bound fluid. Bound fluid is characterized by a fast relaxation time, typically less than 33 ms in sandstones and 100 ms in carbonate rocks. Therefore, thewait time for a bound fluid log can be much shorter than for standard NMR logs, with the result that logging speeds are much faster. See: nuclear magnetic resonance measurement