05.07.2009

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.

The wash boring method is frequently used in sands and silts to either advance a casing or collect soil samples. Water is pumped down the drill rods under pressure and discharges through ports in the drill bit and carries the soil up to the surface in the annulus between the rod and the boring wall or casing.

The time when drilling or completion operations are suspended so that the cement in a well can harden sufficiently.