Difficulty: Moderate
Instructions
Things You'll Need:
- Stopwatch
- Chemical marker
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Step 1
When the drilling mud is introduced to the borehole, start timing. When the mud hits the bottom end of the drill stem, stop timing. This is the down time.
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Step 2
Introduce a chemical marker into the drilling mud and start the stopwatch.
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Step 3
When the chemical marker returns to the surface, stop the stopwatch. This is the marker time.
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Step 4
Subtract the down time from the marker time. The result is the lag time.
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Step 5
Subtract the down time from the total time it takes for a marker introduced into the drilling mud at the surface to travel to the bottom of the borehole and back to the surface.
