"If we think that the 190 billion barrels can be attributed to genuine reserve growth, the USGS estimate of an addition of 730 billion barrels from reserve growth between 1995 and 2025 is on track so far. This does not necessarily mean that reserve growth will continue or discontinue to happen in the future as it did in the past."

I concur. And the good news is that the rate of Reserve Growth is increasing. When i tracked the 18 URR Estimates for my study, i found that Reserve Growth including Discoveries averaged 48-Gb/annum. However, in this decade, we are seeing phenomonal Reserve Growth incl Discoveries of 140-Gb/yr.

Since we know Discoveries since Y2k have been minimal and that the technology for assessing fields is vastly improved, we can deduce that Price is the determining forcing agent. Plus $30/barrel pricing allows extraction of hundreds of fields that were deemed uneconomical. IEA presently determines that each $5 increase in the real price of oil will add about 100-Gb to global URR. The usgs study forecast that Reserve Growth would grow at 24-Gb/yr. But as we know from EIA Outlooks of the era, their premise was based on pricing regimes much less than we are seeing for this decade. The acceleration of real oil prices in the first decade of the new millenium has been the greatest factor in their underestimation of events.

On Jan 1st 1996 (effective date of usgs-2000), the global URR stood at 1720-Gb in my study. Today, global URR is 3010-Gb ... an increase of 118-Gb/yr.

Again, i caution that i have used Reserve Growth in a fashion that includes Discoveries. The Discovery portion, tiny component as it is, should be discounted for an accurate appraisal of their achivement of targets...

It is clear that usgs underestimated Reserve Growth and overestimated Discoveries. Another factor for discrepancies is that the usgs study assumed a URR of 3123-Gb for 1996. They were somewhat ahead of their time in defining reserves and resources as part of URR that conventional estimates only adopted later. In short, the USGS was counting discoveries and non-conventional oil already in 1996 that some estimates still today do not recognize. The concensus of URR Estimates is in 2007 just attaining the magnitude assumed by usgs for 1996. Today btw, the EIA assumes a URR of 4036-Gb, an increase of 83-Gb (incl Discoveries) since 1996. So, by almost every parameter, the USGS is on target.

The heavy blue line is URR:

please click link for legend and footnotes - http://trendlines.ca/urr.htm