casing patch

1. n. [Well Workover and Intervention]
A downhole assembly or tool system used in the remedial repair of casing damage, corrosion or leaks. Casing patches are most frequently used as short- to medium-term repairs that enable production to be resumed until a major workover operation is scheduled. In some cases, such as in depleted wells nearing the end of viable production, a casing patch may be the only economic means of safely returning the well to production.