Torque & Drag Calculator

Predicting pick-up and slack-off weights lets you spot hole problems early and stay within rig and pipe limits. RIGCALC uses a section-by-section soft-string model with buoyancy and friction.

Formulas

Buoyancy factorBF = 1 − MW / 65.5

Section dragDrag = μ × Normal force

TorqueT = μ × N × r

Worked example

GIVEN

Mud weight 10 ppg
Air weight of string 200,000 lbf (vertical)

WORKING

BF = 1 − 10 / 65.5 = 0.847
Buoyed weight = 200,000 × 0.847

Rotating hookload ≈ 169,500 lbf (plus block weight)

FAQ

What friction factor should I use?

Typical starting values: 0.20–0.25 cased hole, 0.25–0.35 open hole with WBM, lower with OBM. Calibrate against actual pick-up/slack-off.

Run it with your well data

Field & Metric units, works offline, save and share results with your crew.

Kill Mud Weight Calculator Kill Sheet Calculator Kick Tolerance Calculator Tubing Movement Calculator

Reference only. Always verify against your company procedures and well-control certification.