Well · Exploration
Mud Logging Unit
A cabin at the rig where geologists log the cuttings and the gas that come up in the drilling mud.
What it does
It describes the rock drilled, measures total gas and its components with a gas chromatograph, and tracks drilling parameters to spot hydrocarbon shows, pressure changes, kicks and losses in real time.
Basics
| Gas | Total gas and C1 to C5 by chromatograph |
| Cuttings | Lithology and shows under microscope and UV |
| Lag time | Time for cuttings to travel from bit to surface |
| Safety | H2S detection |
Common failures
- Wrong lag time, so cuttings and gas are assigned to the wrong depth
Troubleshooting
- Symptom
- Shows do not match the logs
- Likely cause
- Lag time drifted with hole size or pump rate
- What to check
- Recalibrate lag with a marker and correct depths