Drill Stem Test

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In oil and natural gas extraction, the drill stem includes the drill pipe, drill collars, bottomhole assembly, and drill bit. A drill stem test (DST) is a procedure for testing the surrounding geological formation through the drill pipe.

During normal drilling, fluid is pumped through the drill stem and out the drill bit. Instead, in a drill stem test, fluid from the formation is recovered through the drill stem, while several measurements of pressure are being made.^[1]

The basic drill stem test tool consists of a packer or packers, valves or ports that may be opened and closed from the surface, and two or more pressure-recording devices. (A packer is an expanding plug which can be used to seal off sections of the open well, here to isolate them for testing.^[2]) The tool is lowered on the drill pipe to the zone to be tested. The packer or packers are set to isolate the zone from the drilling fluid column, and testing measurement begins.

[edit] See also

• Oil well
• Drilling rig

[edit] External links

• A good DST definition provided by Northstar Drillstem Testers

[edit] Notes

1. ^ Society of Petrophysicists & Well Log Analysts glossary, accessed on 12 September 2006 at http://www.spwla.org/library_info/glossary/reference/glossd/glossd.htm
2. ^ Society of Petrophysicists & Well Log Analysts glossary, accessed on 12 September 2006 at http://www.spwla.org/library_info/glossary/reference/glossp/glossp.htm