Advanced Petrophysics · Module A6
Advanced Saturation and Wettability Risk
The diagnostic signs that Archie has broken down and what to do about them: shaly-sand model failure modes, wettability measurement and its effect on the saturation exponent, low-resistivity pay, conductive minerals, fresh formation water, gas and heavy oil, and a saturation-model risk register.
- Level
- Advanced
- Position
- Module 6 of 8
- Video
- About 22 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
- Diagnostic signs that Archie has broken down
- Failure modes of the shaly-sand models
- Wettability measurement and the saturation exponent
- Low-resistivity pay and conductive minerals
- Fresh formation water, gas and heavy oil
- A saturation-model risk register and escalation points
Learning outcomes
After the module you should be able to:
- Diagnose where Archie breaks down and carry saturation and wettability risk.
- Recognise the conditions under which a saturation model fails
- Assess the effect of wettability on the saturation exponent
- Record saturation-model risk so that it reaches the decision
A short preview
In a strongly water-wet rock the saturation exponent n is close to 2. In an oil-wet rock it can be much higher, because the water sits in disconnected pockets that carry little current. Since Sw = (a·Rw / (φᵐ·Rt))^(1/n) and the bracket is below one, a larger n gives a larger Sw: using n = 2 in an oil-wet rock understates water saturation and overstates the hydrocarbon in place. Measuring n on preserved or restored-state core is the direct way to know.
Who it is for
Experienced petrophysicists and geoscientists who interpret complex reservoirs and present interpretation risk to asset teams and management.
Prerequisites: The Intermediate Petrophysics track, or several years of interpretation work.
Take the module in the Learning Hub
Advanced Petrophysics: Eight advanced modules with narrated lessons; quizzes and certificate eligibility come with the certified option. The lesson opens in the Learning Hub once the track is purchased; graded quizzes and the certificate come with the certified option.