Energy Return on Energy Investment for Global Oil now faces sharp decline

OILDRUM.COM: We estimate that EROI at the wellhead was roughly 26:1 in 1992, increased to 35:1 in 1999, and then decreased to 18:1 in 2006. These trends imply that global supplies of petroleum available to do economic work are considerably less than estimates of gross reserves and that EROI is declining over time and with increased annual drilling levels. Our global estimates of EROI have a pattern similar to, but somewhat higher than, the United States, which has better data on energy costs but a more depleted resource base.

SHOOT: Not a good time for it to happen is it? It basically means we are paying more and more money just to extract energy [oil] and we're getting less bang for our buck, because all the higher quality oil has been extracted already. What remains is sulphur heavy, harder to reach, tougher and more expensive to refine.

clipped from netenergy.theoildrum.com Economies are fueled by energy produced in excess of the amount required to drive the energy production process. Therefore any successful society’s energy resources must be both abundant and exploitable with a high ratio of energy return on energy invested (EROI). “What are the reasons for the decline in EROI estimates, especially since 1999?” They offer two solutions: 1) technology is seemingly being outpaced by depletion, and/or 2) increasing the annual drilling rate decreases the drilling efficiency. The drilling intensity decreased during the early and mid 1990s when EROI was actually increasing, but has increased since 1999. This has led to a sharp decrease in drilling efficiency (barrels found/produced per well drilled).