1. n. 
Water in the pore space that does not flow under normal reservoir conditions. Bound water does not flow on primary or secondary production, injection, or invasion unless the rock wettability is altered. When used in connection with a nuclear magnetic resonance measurement, the term refers to all the water that is not free to move. This includes capillary-bound water and clay-bound water. However, water in mineral hydrates is not included as it relaxes too fast to be measured by nuclear magnetic resonance (NMR). In practice, bound water is defined as the water signal below a certain cutoff, typically 33 ms in sandstones and 100 ms in carbonates. When used in connection with the dual water model, the term refers to the clay-bound water only. In the Hill-Shirley-Klein model, the term is known as the hydration water.