Reserves and Forecasting · Module R7
Probabilistic Reserves and Aggregation
Reserves are distributions, and adding distributions is not adding numbers. The module derives categories from simulation and from decline-fit uncertainty, applies chance factors correctly, and compares arithmetic portfolio totals with probabilistic aggregation and the role dependence plays between them.
- Level
- Intermediate
- Position
- Module 7 of 8
- Video
- About 19 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
- Percentiles to 1P/2P/3P
- Bootstrap uncertainty in a decline forecast
- Risking the mean, not a percentile
- Arithmetic versus probabilistic aggregation
- Dependence and duplicate cases in roll-ups
Learning outcomes
After the module you should be able to:
- Derive 1P/2P/3P from a stated method and aggregate without bias.
- State the method behind every reserves category
- Explain the bias of summed P90s and P10s
- Report a portfolio total with its aggregation method
A short preview
Adding percentiles across independent fields distorts the range. Take ten identical, independent fields each with a P90 of 2 and a P10 of 6 million barrels. Summing gives 20 and 60, but the chance that all ten come in low together is tiny, so the true portfolio P90 is well above 20 and the true P10 well below 60. Means, by contrast, add exactly, which is why expected values are the right currency for portfolio arithmetic.
Who it is for
Reservoir and production engineers, petrophysicists and geoscientists who estimate, review or report reserves and production forecasts.
Prerequisites: None required; working familiarity with production data and volumetrics helps.
Take the module in the Learning Hub
Reserves and Forecasting: Specialty course, sold separately: eight modules from PRMS classification and decline curves to type wells, material balance, aggregation and the reserves report. The lesson opens in the Learning Hub once the track is purchased; graded quizzes and the certificate come with the certified option.