Wash over:To release pipe that is stuck in the hole by running washover pipe.
The washover pipe must have an outside diameter small enough to fit into the borehole but an inside diameter large enough to fit over the outside diameter of the stuck pipe.
A rotary shoe, which cuts away the formation, mud, or whatever is sticking the pipe, is made up on the bottom joint of the washover pipe, and the assembly is lowered into the hole.
Rotation of the assembly frees the stuck pipe.
Several washovers may have to be made if the stuck portion is very long.