1. adj. [Formation Evaluation, Enhanced Oil Recovery]

Pertaining to the preference of a solid to be in contact with an oil phase rather than a water or gas phase. Oil-wet rocks preferentially imbibe oil. Generally, polar compounds or asphaltenes deposited from the crude oil onto mineral surfaces cause the oil-wet condition. Similar compounds in oil-base mud also can cause a previously water-wet rock to become partially or totally oil-wet.

See related terms: drainage,  imbibition,  water-wet,  wettability