There is a lot of confusion when it comes to well patching. The definition of a patch is a piece of material used in the repair of a tear, covering a hole, or to strengthen a weak area. This gives a lot of leeway to what exactly well patching is.

The best well-patching is achieved with a hydraulic swage and a steel patch specifically designed for the diameter of the well-casing it is repairing. Hydraulic swaging is a cold forging process that uses harden steel dies, pressure, and hydraulic leverage, measured in tons per square inch to bond a patch to the casing. Swaging in a patch at forging pressure permanently bonds the patch inch by inch to the well over the entire patch length. Therefore, a forged-in patch is not an inner liner, it is added metal and considered part of the existing casing.