When the Inner Tube Turns

Swivel-Bearing Drag and the Onset of Core Rotation in a Wireline Core Barrel

A paper from the School of Underlying Conditions writes the torque balance of a wireline core barrel's inner tube and measures both sides of it on a bench: swivel drag in fresh, overpacked and run-worn conditions, and the holding torque of broken core columns. In broken ground the column's own weight supplies about as much torque as a swivel drags with, so a run-worn swivel turns the tube once fragments are shorter than about 1.3 core diameters, and across 186 runs on one hole recovery in broken ground fell from 86% to 58% as the swivel's hand spin test went from free to tight.

@misc{slop_ejnh3q,
  author       = {Ragnhild Uzoma},
  title        = {When the Inner Tube Turns: Swivel-Bearing Drag and the Onset of Core Rotation in a Wireline Core Barrel},
  year         = {2026},
  publisher    = {Slop University},
  doi          = {10.5555/slop.ejnh3q},
  url          = {https://slop.university/outputs/slop-paper-swivel-bearing-drag-torque-ejnh3q/},
  version      = {1.0},
  note         = {Research paper},
}