What is a drillstem test?
The drillstem testing tool consists of packers and a surface-operated downhole valve run into the well on drill pipe. While the drill string is run, the valve is closed, excluding wellbore fluids from the pipe. Once on bottom, the packers are set to isolate the zone from the mud column, and the valve is opened to allow formation fluids to enter the drill pipe. After initial flow to relieve the hydrostatic pressure on the formation, the valve is closed, allowing the formation to re-pressure the well bore between the packers. This process is repeated while pressures are recorded for subsequent flow and shut-in periods.
