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903 Well Site Completion and Servicing Safety
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Conducting Drill Stem Test

To determine the production potential of a formation, the operator may order a drill stem test (DST).

Drill Stem Testing

The Drill Stem Test (DST) crew begins by assembling the test tool on the lower end of the drill stem. This tool is made up of several parts designed to isolate and test the formation at the bottom of the well. Once the tool is completely assembled, it is lowered carefully to the bottom of the wellbore using the drill pipe.

After the tool reaches the correct depth, weight is applied to it from the surface. This pressure helps activate and expand a hard rubber sealer known as a packer. The packer creates a tight seal between the drill stem and the wellbore, blocking the flow of fluids from other parts of the formation. This isolation is important to get accurate pressure readings from the target zone.

Once the packer is set and the tool is in position, ports on the tool are opened. These ports allow fluids from the formation to enter the tool, and the pressure is measured. This step is critical for understanding the natural pressure within the formation and how it behaves under different flow conditions.

The information collected during this process helps engineers and geologists determine whether the formation contains oil, gas, or water, and whether it can be produced in a safe and efficient way. If the formation shows promising pressure and fluid flow, the well may move forward into full production planning.

Knowledge Check Choose the best answer for the question.

1-2. What is the purpose of the Drill Stem Test (DST)?