Unconventional Reservoirs · Module U5
Calibrating to core and the range
Core is the reference every log TOC answers to, with scatter of its own. The module pairs plugs to log depths within a tolerance, fits the uranium regression, the Schmoker densities, a maturity from the overlay and a straight-line calibration of the fused curve, and explains when to turn down a fit whose statistics look good. It closes with the preview band and the parameter uncertainty card, which carry TOC uncertainty through porosity, saturation and net pay.
- Level
- Advanced
- Position
- Module 5 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
- Pairing core to log within a depth tolerance
- Uranium and density fits from core
- A maturity from the overlay against core
- Calibrating the fused curve
- Excluding a plug and recording why
- The TOC band and the uncertainty card
Learning outcomes
After the module you should be able to:
- Calibrate to core with fit statistics and residuals you have looked at, and state a P10 to P90 TOC band.
- Accept or reject a core fit from its residuals, not only its R²
- Carry TOC uncertainty through to porosity and net pay
A short preview
A calibration can have an excellent R² and still be wrong for one zone. Fit a single line of core TOC against log TOC across an oil-prone source rock and a gas-bearing one, and the line has to serve both. If the log over-reads the gas zone by a quarter and the oil zone by a twentieth, the fitted line lands between them: the gas zone stays high and the oil zone ends up slightly low. Plotting the residuals zone by zone shows the problem at once; the R² never will.
Who it is for
Petrophysicists, geoscientists and reservoir engineers who evaluate organic shales and source rocks from logs and core, and carry TOC, net pay and gas in place into appraisal and development decisions.
Prerequisites: The Intermediate track, or working experience with shale volume, porosity and water saturation; the Geomechanics course is recommended before U8. The hands-on steps use the Organic Matter workspace in Formation Evaluation, and the brittleness steps in U8 use the Geomechanics workspace, available from the Professional plan.
Take the module in the Learning Hub
Unconventional Reservoirs: Specialty course, sold separately: eight modules that evaluate an organic shale from logs and core, from TOC methods fused and calibrated to core, through kerogen-corrected porosity and net pay, to free and adsorbed gas in place and brittleness. The lesson opens in the Learning Hub once the track is purchased; graded quizzes and the certificate come with the certified option.