Every Perf-Hub engine implements a method published in the open well engineering literature. These pages explain where the formulas come from, what each model assumes and where it stops holding — with full references.
How a survey becomes a position in space, how a well path is designed to a target, and why measured azimuth needs correcting before any of it.
How tension, torque and side force are computed along the string — from Johancsik's soft-string model to 3D stiff-string with unilateral contact.
How annular pressure loss, ECD and cuttings transport are computed — from Bourgoyne's rheological model to Larsen's critical transport velocity, with surge/swab and eccentricity.
How critical rotary speeds, self-excited stick-slip, lateral whirl and rotating-bending fatigue are predicted — from the modal eigenproblem to the Detournay-Defourny RGD model.
How positional uncertainty is computed for a directional well and how it drives separation from offset wells — from the full MWD Rev. 5.11 error model to the ISCWSA pedal-curve rule.
Dawson/Paslay sinusoidal and Wu/Chen helical buckling limits, how torque cuts into the critical load, and how those limits carry over into fatigue and triaxial stress at the pipe wall.
The engines are checked live against public industry benchmarks on the validation page. See the validation