Misrun

The reasons for cold shut or misrun may be too thin sections, improper gating system, slow and intermittent pouring, poor fluidity of metal.

When wall thickness is decreased to less than 1/16 in., adequate mold filling becomes almost impossible, except for extremely short distances, and misruns result because of the freezing of metal before the mold is filled.

A misrun is caused when the metal is unable to fill the mould cavity completely and thus leaves unfilled cavities.

If the molten metal is too cold or casting is too thin, entire mould may not be filled during pouring before the metal starts solidifying and result in misrun.

The experience of most drillstem testing companies indicates that the chance of a misrun in a poorly prepared hole is approximately 30 percent, whereas the chance of a misrun in a well-prepared hole has been cut down to roughly 15 percent.

In this test, the pressure curve shows clearly that a seal was not affected; therefore, this is a misrun.

Follow Schlumberger procedures for recovering guns in the event of a misrun.

When the DST tool is set, if fluid does not stay at the surface on the outside of the hole or the drill pipe, then you have a misrun.