Intermediate Petrophysics · Module I3
Porosity Calibration Workflow
Total and effective porosity from density, neutron, sonic and NMR logs, then calibration to core: depth matching core to log, choosing the right core porosity, handling scatter on the log–core crossplot, and facies-specific transforms. The deliverable is a porosity range backed by evidence, not a single curve.
- Level
- Intermediate
- Position
- Module 3 of 8
- Video
- About 20 minutes, narrated
- Format
- Narrated video lesson and slide reading view; with the certified option, a quiz whose pass unlocks the next module.
What the module covers
- Total versus effective porosity
- Matrix and fluid assumptions in density porosity
- Neutron lithology effects and the density–neutron crossplot
- Sonic and NMR porosity
- Core-to-log depth matching and choosing a core porosity
- Facies-aware transforms, and reconciling methods that disagree
Learning outcomes
After the module you should be able to:
- Calibrate porosity with facies-aware evidence and uncertainty bounds.
- Calibrate log porosity to core and explain the remaining scatter
- Use facies-specific transforms where one transform does not fit
- Report porosity as a range with its evidence
A short preview
Routine core porosity is often measured on cleaned, oven-dried plugs at low confining stress. Drying drives off clay-bound water, so the result sits closer to a total porosity than an effective one, and the low stress tends to make it slightly high compared with the rock in place. Before core is used to calibrate a log, both points need deciding: which porosity the log model is meant to deliver, and whether the core needs a stress correction. Skipping that step biases every calibrated value in the same direction.
Who it is for
Petrophysicists and geoscientists with some interpretation experience, and engineers who review petrophysical inputs before they reach a volumetric or simulation model.
Prerequisites: The Basic Petrophysics track, or equivalent working experience.
Take the module in the Learning Hub
Intermediate Petrophysics: Eight applied modules with checkpoints; with the certified option, pass each quiz to unlock the next lesson. The lesson opens in the Learning Hub once the track is purchased; graded quizzes and the certificate come with the certified option.