Reserves and Forecasting · Module R4
From Decline to EUR — Economic Limit and Remaining Reserves
A good fit is not yet a reserves number. This module shows how the end of a forecast is set: an economic limit calculated from prices and costs, a terminal decline that keeps hyperbolic tails realistic, a maximum well life, and an effective date that lines up with the history cut-off.
- Level
- Intermediate
- Position
- Module 4 of 8
- Video
- About 17 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
- EUR, cumulative and remaining volumes
- Calculating an economic limit rate
- Modified hyperbolic and terminal decline
- How price changes move reserves
- Annual profiles for the cash-flow model
Learning outcomes
After the module you should be able to:
- Turn a fit into EUR and remaining reserves with its limits stated.
- Compute an economic limit from a well's own costs
- Choose and justify a terminal decline
- Report remaining reserves at a stated effective date
A short preview
The economic limit is the rate at which a day's net revenue just pays the day's fixed operating cost. If fixed costs are $800 a day and each barrel leaves a margin of $40 after royalty, differential and per-barrel costs, the limit is 800 / 40 = 20 barrels a day. Halve the margin with a price fall and the limit doubles to 40, cutting years from the end of the forecast — which is why every reserves number carries a price assumption.
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.