Stuck Pipe Calculator
Calculate freeing force, pipe stretch, and free point depth for stuck pipe incidents
Stuck Pipe Analysis
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Stuck Pipe Types
- Differential: Pipe stuck against permeable formation
- Mechanical: Key seat, ledges, undergauge hole
- Pack-off: Cuttings, cavings, cement, lost circulation material
Results
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Drill Pipe Stretch Constants
| Pipe Size | Weight (lb/ft) | Stretch Constant |
|---|---|---|
| 3-1/2" DP | 13.3 | 9.625 x 10^-8 |
| 4-1/2" DP | 16.6 | 6.890 x 10^-8 |
| 5" DP | 19.5 | 5.235 x 10^-8 |
| 5" HWDP | 50 | 2.860 x 10^-8 |
| 6-1/2" DC | 96 | 0.930 x 10^-8 |
Formula Reference
Pipe Stretch
Stretch (in) = (F x L) / (A_s x E) x 12
Or using stretch constant:
Stretch (in) = K x F x L
Where:
F = Pull force (lbs)
L = Free pipe length (ft)
A_s = Steel cross-sectional area (in2)
E = Young's modulus (30 x 10^6 psi)
K = Stretch constant
Free Point Depth
Free Point (ft) = Stretch (in) / (K x Overpull)
Or: Free Point = (A_s x E x Stretch) / (12 x F)
Steel Cross-Sectional Area
A_s = (PI/4) x (OD^2 - ID^2)
Differential Sticking Force
F = dP x A_contact x mu
Where:
dP = Differential pressure (psi)
A_contact = Contact area (in2) = OD x L_stuck x theta
mu = Friction coefficient (0.2-0.4 typical)
theta = Arc of contact (radians, ~1 for filter cake)
Stretch Constant
K = 1 / (A_s x E / 12) = 12 / (A_s x E)