 The testing equipment is run into the well and the zone of interest is isolated using inflate or compression-set packers, depending on your requirements and drilling conditions.Depending on testing objectives and scope of work, drill stem testing may also be performed in combination with various other exploration and completion process such as fluid loss control and well control, closed chamber tests, well stimulation, and a combination of DST and TCP.During normal well drilling, drilling mud is pumped through the drill stem and out of the drill bit.