Circulating tool for equalizing pressure and fluid flow
The ported bypass sub is used to equalize pressure and fluid flow around the tool. Specifically, the sub establishes communication between the fluids in the drillpipe and pressure and fluid flow in the drillstring. The sub is typically run above the WELL PATROLLER validation tool to provide an additional means of equalizing pressure and fluid flow around the tool should it fill with debris while pulling out of hole.
The sub can also function as a drillpipe drain sub.