About the Tubing Anchor Calculator
This tool estimates where to set a tubing anchor relative to the pump depth and checks whether the selected anchor rating is adequate for the calculated axial load. It is useful for production engineers, artificial lift planners, and field personnel doing preliminary tubing string and anchor planning.
How to use this calculator
- Enter the pump or seating nipple depth in feet.
- Enter how far above the pump the anchor should be set.
- Enter the planned surface pull or set tension.
- Select a tubing size, or choose custom tubing and enter its weight and OD.
- Enter fluid specific gravity, safety factor, extra load, temperature change, thermal restraint, and anchor rated holding force.
- Click Calculate to view anchor depth, buoyed tubing weight, load estimates, and rating utilization.
How it works
The calculator first places the anchor by subtracting the anchor-above-pump offset from the pump or seating nipple depth. For example, a 6,500 ft pump depth with a 100 ft offset gives a recommended anchor setting depth of 6,400 ft measured depth.
Tubing load is estimated from the tubing nominal weight, anchor depth, and a buoyancy factor based on produced fluid specific gravity. Fluid density is calculated as specific gravity times 62.4 lb/ft³, and the buoyancy factor is approximated as 1 minus fluid density divided by 490, with a minimum value of 0.05.
The estimated service load adds buoyed tubing weight, surface set tension, extra cyclic or friction load, and a simplified thermal allowance. The thermal allowance uses steel modulus, thermal expansion, tubing steel area estimated from nominal weight, temperature change, and the selected restraint factor.
Required holding force is the estimated service load multiplied by the design safety factor. Utilization compares that required holding force with the entered anchor rated holding force, and the suggested rating is the rating that would keep utilization at 80%. Results are educational estimates only and should not replace manufacturer guidance or professional engineering review.
Example calculation
Using the default-style inputs: pump depth 6,500 ft, anchor offset 100 ft, surface tension 6,000 lbf, 2.375 in tubing at 6.50 lb/ft, fluid SG 1.05, safety factor 1.25, extra load 2,500 lbf, temperature change 30°F, light restraint 25%, and a 40,000 lbf anchor rating. The anchor depth is 6,500 − 100 = 6,400 ft. The buoyed tubing weight is about 36,038 lbf, thermal allowance is about 2,794 lbf, and estimated service load is about 47,331 lbf. With the 1.25 safety factor, required holding is about 59,164 lbf, which exceeds a 40,000 lbf rating.
Frequently asked questions
How far above the pump should a tubing anchor be set?
The calculator accepts any offset less than the pump depth, but common preliminary values are often 50 to 200 ft above the pump or target device. The final location depends on completion design and manufacturer recommendations.
What does buoyed tubing weight mean?
Buoyed tubing weight is the effective tubing weight in produced fluid. Denser fluid provides more buoyancy, reducing the apparent axial weight the anchor must help support.
Why does temperature change affect the holding load?
If tubing movement is restrained, thermal expansion or contraction can create axial stress. The calculator adds a simplified thermal load based on temperature change and the selected restraint factor.
What does anchor utilization mean?
Utilization is the required holding force divided by the entered anchor rated holding force. Values over 100% indicate the calculated requirement exceeds the selected rating.
Can this calculator select the final tubing anchor for a well?
No. It is for preliminary planning only. Final selection should consider well deviation, tubing grade, connection limits, corrosion, scale, temperature profile, operating loads, and anchor manufacturer data.