When a tensile load is applied into a drillstring, it results in elongation of the drillstring.
The formula to determine pipe elongation is listed below;
Oilfield unit
e = (L x T) ÷ (735,000 x W)
Where;
e = elongation, inch
L = length of drill string, ft
T = tensile load, lb
W = drill string weight, lb/ft
Metric (SI) unit
e = (L x T) ÷ (26.7 x W)
Where;
e = elongation, mm
L = length of drill string, metres
T = tensile load, kN
W = drill string weight, kg/m
Note: The equations are taken from API RP 7G 16th Edition, August 1998.
