1.
n. [Geology]
Water that occurs naturally within the pores of
rock. Water from fluids introduced to a
formation through drilling or other interference, such as
mud and seawater, does not constitute formation water. Formation water, or interstitial water, might not have been the water present when the rock originally formed. In contrast, connate water is the water trapped in the pores of a rock during its formation, and may be called
fossil water.