DST

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    • topic:: 00 Petroleum Engineering00 Petroleum Engineering
      #MOC / notes on petroleum and reservoir engineering (PE/RE) including resources classification
    • updated:: 2022-05-11 Private or Broken Links
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    • reviewed:: 2022-05-11 Private or Broken Links
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    • #LiteratureNote

  • DST are well tests conducted with the drillstring still in the hole.

    • these tests are usually conducted with a downhole shut-in tool that allows the well to be opened and closed at the bottom of the hole with a surface-actuated valve.

  • One or more pressure gauges are customarily mounted into the DST tool and are read and interpreted after the test is completed.

    • The tool includes a surface-actuated packer that can isolate the formation from the annulus between the drillstring and the casing, thereby forcing any produced fluids to enter only the drillstring.
    • By closing in the well at the bottom, afterflow is minimized and analysis is simplified, especially for formations with low flow rates.

  • DST are typically performed on exploration wells, and are often the key to determining whether a well has found a commercial hydrocarbon reservoir

    • The most common test sequence consists of a short flow period, perhaps 5 or 10 minutes, followed by a buildup period of about an hour that is used to determine initial reservoir pressure. This is followed by a flow period of 4 to 24 hours to establish stable flow to the surface, if possible, and followed by the final shut-in or buildup test that is used to determine permeability thickness and flow potential.

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