Drill pipe elongation will occur because the higher bottom hole temperature.
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Rule of Thumb
Pipe will elongate approximately 0.83 inc per 100 ft of length, per 100 degree F increase in Temperature.
We need to know the surface temperature and bottom hole temperature in order to determine pipe elongation.
The following formulas are used to determine pipe elongation.
Average Temperature = (Bottom Hole Temperature + Surface Temperature) ÷ 2
∆ Temperature = Average Temperature – Surface Temperature
Pipe Elongation = (L ÷ 100) × (∆ Temperature ÷ 100) × 0.83
Where
Average Temperature, Bottom Hole Temperature and Surface Temperature are in F.
Pipe Elongation is in inch.
L is total length in feet.
Example
Determine pipe elongation from the following information.
Total length of pipe is 10,000 ft.
Surface temperature is 80 F.
Bottom hole temperature is 375 F.
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Average Temperature = (80 + 375) ÷ 2 = 227.5 F
∆ Temperature = 227.5 – 80 = 147.5 F
Pipe Elongation = (10,000 ÷ 100) × (147.5 ÷ 100) × 0.83 = 122.43 inch
