1. n. [Well Workover and Intervention]

An equilibrium reaction between a metal ion and a complexing agent. Chelation reactions are characterized by the formation of more than one bond between the metal and a molecule of the complexing agent. Chelation results in the formation of a ring structure incorporating the metal ion. In the oil field, chelation is often used to enhance stimulation treatments and to clean surface facilities.

See: chelate,  chelating agent