Unconventional Reservoirs · Module U6
Kerogen and uranium in the interpretation
Once TOC is known, kerogen and uranium have to come out of the rest of the interpretation. This module corrects the density, neutron and sonic porosity models for kerogen at every sample, explains why total porosity in a source rock uses a zero shale porosity, replaces the total gamma ray with a computed gamma ray so uranium is not read as clay, treats kerogen as an end member in the probabilistic solver, and adds a TOC cut-off to net pay.
- Level
- Advanced
- Position
- Module 6 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
- Kerogen volume from TOC and back
- Kerogen corrections on the density, neutron and sonic
- Total porosity and a zero shale porosity
- Computed gamma ray for shale volume
- Kerogen in the probabilistic solver
- Saturation on corrected porosity, and the TOC cut-off
Learning outcomes
After the module you should be able to:
- Report porosity, shale volume and net pay that count kerogen as kerogen and uranium as uranium.
- Correct a porosity log for kerogen and check it against core
- Explain why a uranium-driven gamma ray overstates shale volume
A short preview
Organic matter concentrates uranium, and uranium alone can carry the gamma ray past any shale cut-off. A spectral tool separates the thorium, potassium and uranium contributions, and the computed gamma ray removes the uranium share, about 8 API units per ppm. A source rock reading 150 API with 9 ppm uranium has a computed gamma ray near 77 API. With clean and shale endpoints of 15 and 135, the linear shale volume falls from 1.0 to about 0.5, and rock that every net pay cut-off rejected can come back into play.
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.