Estimated ultimate recovery
- Abbreviation
- EUR
- Also known as
- EUR, estimated ultimate recoverable
Estimated ultimate recovery (EUR) is the total amount of oil or gas a well, field or reservoir is expected to produce over its entire life, counting what has already been produced plus what remains to be recovered under a given development plan.
What is estimated ultimate recovery?
Estimated ultimate recovery, or EUR, answers the question: how much will this well ultimately produce? It is the sum of the oil or gas already produced and the remaining volume expected to be produced before the well is abandoned, under assumed economic and technical conditions. EUR is usually stated per well, in barrels of oil, thousand cubic feet of gas, or barrels of oil equivalent, but it can also be given for a field or reservoir.
How EUR is estimated
- Decline curve analysis. Production history is fitted to a mathematical decline model and projected forward to an economic limit. This is the most common method for producing wells.
- Type curves. For new wells, especially in shale plays, EUR is often estimated from the average performance of comparable wells.
- Reservoir simulation and material balance. Engineering models of the reservoir estimate how much can be recovered under a given development plan.
- Volumetric estimates. Before production, EUR can be estimated from the volume of oil or gas in place and an expected recovery factor.
EUR is a forecast and changes as production data accumulate. Early estimates for shale wells, whose steep early declines make projection difficult, can differ substantially from what wells eventually produce.
EUR, reserves and recovery factor
- EUR vs. reserves. Under the SPE Petroleum Resources Management System, reserves are the remaining quantities expected to be commercially recovered from a given date forward. EUR includes both cumulative production to date and those remaining quantities.
- EUR vs. recovery factor. EUR is a volume. Recovery factor is a percentage: the share of the oil or gas originally in place that is, or is expected to be, recovered. Dividing EUR by the original volume in place gives the recovery factor.
Why EUR matters
EUR is one of the main numbers behind the economics of a well. Together with drilling and completion costs, lease operating expense and prices, it determines whether a well pays back and by how much. Operators compare EURs to judge completion designs, well spacing and treatments; lenders and investors use them to value assets.
Treatments that improve early cleanup after hydraulic fracturing, or that slow a well’s decline, are evaluated by their effect on EUR as well as on initial production.
EUR at Locus
Locus reports field results for its SUSTAIN frac surfactant in terms of cumulative production and EUR, and describes its AssurEOR treatments as flattening decline curves to extend well life.
Frequently asked questions
Usually by fitting early production to a decline model, often hyperbolic transitioning to exponential, and projecting it to an economic limit, and by comparison with type curves from similar nearby wells. Because shale wells decline steeply at first, early EUR estimates carry considerable uncertainty.
EUR is the total volume a well or field is expected to produce. Recovery factor is that volume expressed as a percentage of the oil or gas originally in place.
Yes. EUR is re-estimated as production history grows, and it can change with prices, operating costs, workovers and treatments that alter the well’s decline.
Sources
- Petroleum Resources Management System (PRMS), Society of Petroleum Engineers and co-sponsoring organizations
- estimated ultimate recovery, SLB Energy Glossary
- Decline curve analysis, SPE PetroWiki