Rock Typing and Permeability · Module K3
Permeability from porosity and irreducible water
Published transforms estimate permeability from porosity and irreducible water saturation. The module works through Timur, Tixier, Morris-Biggs, Kozeny-Carman and the Coates free-fluid form, converts their constants to the fractions the platform uses, and shows why the saturation input must be irreducible water rather than the log water saturation. It ends with calibrating a constant by hand and reading the misfit against core rock type by rock type.
- Level
- Advanced
- Position
- Module 3 of 8
- Video
- About 18 minutes, narrated
- Format
- Narrated video lesson with captions and slide reading view; with the certified option, a quiz whose pass unlocks the next module.
What the module covers
- Irreducible water as a measure of grain surface
- Timur, Tixier and Morris-Biggs constants in fractions
- Kozeny-Carman and the Coates free-fluid form
- Buckles and the bulk volume of irreducible water
- Why log water saturation is the wrong input
- Calibrating by hand and reading the misfit
Learning outcomes
After the module you should be able to:
- Run a published transform on irreducible water, with its constants stated and its misfit against core read unit by unit.
- Convert a published constant from percent to fractions and check it on one sample
- Recognize a misfit that grows with poorer rock as a missing rock type
A short preview
Give five published transforms one rock, with porosity 0.20 and irreducible water saturation 0.30, and at their default constants they return 80, 44, 4.4, 87 and 125 millidarcies: Timur, the Tixier oil form, the Morris-Biggs gas form, Coates and Kozeny-Carman. That is a factor of 28 for one rock before any core has been consulted. The saturation input matters as much as the model. Below the free water level the resistivity log reads a water saturation of 1.0 whatever the rock, and a transform fed that value describes the fluid, not the permeability.
Who it is for
Petrophysicists, reservoir engineers and geoscientists who build permeability curves from core and logs, define rock types, and carry permeability into net pay, k·h and saturation-height models.
Prerequisites: The Intermediate track, or working experience with shale volume, porosity and water saturation; Advanced modules A2 and A4 help but are not required. The hands-on steps use the Rock Typing, Permeability estimate, NMR and Neural network permeability workspaces in Formation Evaluation, all available from the Starter plan.
Take the module in the Learning Hub
Rock Typing and Permeability: Specialty course, sold separately: eight modules that turn core plugs and logs into a permeability curve you can defend, from plugs on a stated basis through transforms, NMR and rock types to net pay, k·h and the saturation-height hand-off. The lesson opens in the Learning Hub once the track is purchased; graded quizzes and the certificate come with the certified option.