Drill Stem Testing is the most conventional form of formation testing to determine formation pressure, skin, and fluid flow characteristics, where wells are being allowed to produce water, gas or oil from the target zone.

Testing is performed by exposing the formation to controlled depressurised environments, encouraging flow from the formation. Subsequent shut in periods measure and record recovery periods.

Resulting data sets are analysed by Reservoir Engineers and Hydro Geologists to calculate reservoir permeability and forecast production rates.