Paper presented at the SPE ATCE, Houston, Texas, Oct 2026. Paper Number:SPE-233801-MS

Inconsistent manual zeroing by drillers makes weight on bit (WOB) measurements unreliable. This paper presents an automated method that identifies the hook load corresponding to zero WOB under both static conditions (circulating and rotating with no pipe movement) and dynamic conditions (circulating and rotating with axial pipe movement). Reference hook loads are taken before and after each connection, and a torque and drag model reduces stand-to-stand variability.

The method was validated with surface and downhole data from multiple North American wells, covering vertical, curve and lateral sections. Both autozero approaches were more accurate and less variable than manual zeroing. The driller’s WOB often matched the static estimate more closely than the dynamic one, which suggests that unaccounted axial drag can cause actual WOB to be overestimated.

This is the first dual static and dynamic approach to automatic WOB estimation. It gives a repeatable, objective basis for optimizing drilling parameters, real-time decisions and WOB calibration.