Whether these (expected) physical differences translate in substantially revised estimates of the value of oil resource stocks is another matter. This stock value for any region is the discounted value of a stream of (constant) future oil extraction. As a result, when proven reserve lifetimes are initially large, the impact on resource stock values of adding expected discoveries can be small. The contrasting cases here are Asia Pacific and South & Central America.

It would be useful to have these data on undiscovered resources for individual countries. Unfortunately, comparable country-level data are sparse. USGS (2000), however, provides a detailed country assessment and Table 3 presents results on alternative measures of depletion and genuine saving for the same 10 countries presented in Tables 1a and 1b.

For Azerbaijan, Kazakhstan, Saudi Arabia and Venezuela, the extent of proven reserves is relatively large. What this means is that the large corresponding (proven) reserves to production ratio has a significant bearing already on the value of resource depletion. In the case of Saudi Arabia, for example, for a proven reserve life of some 76 years, this oil depletion value is 14.8% of GNI. In the case of other countries in Table 3 such as Trinidad and Tobago and Russia, however, proven reserves are estimated to imply resource lifetimes roughly within one generation (from the year 2000). For example, Norway’s proven reserve lifetime of 9 years translates in that case into an oil depletion value that is 14.0% of its GNI.

**Table 3: Oil depletion values and genuine saving for selected countries, 2000**

||**GNI**<br>**$ million**|**_Depl_**<br>**_of pro_**<br>|**_etion as func_**<br>**_ven resource _**<br>|**_tion_**<br> **_stock_**<br>|**_Depl_**<br>**_of tot_**<br>|**_etion as func_**<br>**_al resource s_**<br>|**_tion_**<br>**_tock_**<br>|
|---|---|---|---|---|---|---|---|
|||**Reserve**<br>**life**<br>**(****_S_/****_R_)**|**Oil**<br>**depletion**<br>**(% GNI)**|**Genuine**<br>**saving**<br>**(% GNI)**|**Reserve**<br>**life**<br>**(****_S+X_/****_R_)**|**Oil**<br>**depletion**<br>**(% GNI)**|**Genuine**<br>**saving**<br> **(% GNI)**|
|Angola|$7,449|22|51.5%|-11.7%|62|28.6%|11.2%|
|Azerbaijan|$4,987|59|17.9%|-12.8%|116|9.9%|-4.8%|
|Ecuador|$14,530|31|13.7%|3.6%|35|12.8%|4.5%|
|Kazakhstan|$17,038|92|10.2%|-5.5%|150|6.4%|-1.7%|
|Norway|$166,018|9|14.0%|8.2%|20|11.5%|10.7%|
|Russia|$252,972|25|12.9%|15.8%|56|8.1%|20.6%|
|Saudi Arabia|$188,922|76|14.8%|5.3%|102|11.4%|8.7%|
|Sudan|$11,303|9|11.6%|-11.0%|26|8.5%|-8.0%|
|Trinidad & Tobago.|$7,526|17|11.2%|5.4%|37|8.0%|8.7%|
|Venezuela|$115,760|65|8.9%|14.4%|78|7.6%|15.7%|

Notes: “Total reserves” refer to proven + expected reserves. These reserve life estimates are based on assessments of economic and technological feasibility of extraction. Given that these assessments (and the knowledge and assumptions on which they are based) are evolving, such estimates are also subject to change over time.

Source: Authors’ calculations from USGS (2000), World Bank (2011a) As expected, re-estimating reserve lives to include expected undiscovered resources shrinks the value of oil depletion in all cases. Clearly, the extent varies depending in large part on how much expected undiscovered resources add to total reserves. For many of these countries, however, the effect of considering this is to roughly double our estimate of total reserves. The largest absolute 18