『Abstract
　This paper compares and evaluates fourteen contemporary forecasts of global supply of conventional oil and provides some observations on their relative plausibility. Despite the wide range of modelling approaches used and multiplicity of assumptions made, it is shown that forecasts can be usefully compared along two dimensions, namely: shape of future production profile and assumed or implied ultimately recoverable resource of conventional oil. Other differences between forecasts are either secondary or are components of these two parameters. The paper shows how large differences in the assumed size of the resource make relatively little difference to the timing of a global peak in conventional oil production. It also examines the impact of rates of discovery, reserve growth and depletion on the forecast date of peak and shows how forecasts that delay this peak until beyond 2030 rest on assumption that are at best optimistic and at worst implausible.

Keywords: Depletion; Peak oil: Ultimately recoverable resource』

1. Introduction
2. Concepts, definitions and trends
3. Ultimately recoverable resource of conventional oil
4. Overview of contemporary global supply forecasts
5. Framework for comparing global supply forecasts
6. Impacts of rates of discovery, reserves growth and depletion on date of peak
7. Discussion
Acknowledgements
References
Box 1-Different assumptions about the components of global URR
Box 2-Assumed or implied URR, declining rate and date of peak for the peaking forecasts
Box 3-Assumed or implied URR, decline rate and date of peak for the quasi-linear forecasts
Box 4-Depletion rates

表2　2030年までの全石油生産量についての13予想の比較

	2030年の生産量 （100万バレル／日）	2008〜2030年の累積生産量 （10億バレル）	2030年までの全累積生産量
			10億バレル	IEA（2008）による世界URR見積り量の％
IEA WEO 2008	95.0	747	1897	53.0
OPEC 2008	93.5	738	1930	52.8
US EIA	102.8	780	1888	53.9
Shell（Blueprint）	91.4	748	1898	53.0
Shell（Scramble）	85.6	724	1874	52.4
Meling	94.1	764	1914	53.5
Total	93.1	773	1923	53.8
ExxonMobil	105.2	796	1946	54.4
Energyfiles	78.6	748	1898	53.1
LBST	39.3	504	1654	46.3
Peak Oil Consulting	65.0	670	1820	50.9
Campbell	60.0	609	1759	49.2
Uppsala	67.1	697	1847	51.6
Miller	91.5	888	2038	57.0
注： ・2007年までの世界の累積生産量はBP（2008）からとられた。 ・予想はできるだけ全石油についてであるが、液体の範囲は一致するとは限らない。 ・MillerとOPECはNGLからの見積りも含んだ「re-based」を予想している。

表3　世界の累積生産量と累積発見量の予想へのPFC60％を適用

需要の成長量 （％／年）	新発見量 （10億バレル／年）	埋蔵量の成長量 （10億バレル／年）	生産量のピーク年	ピーク時の累積発見量
1.0	15	0	2021	2593
1.0	15	20	2032	3269
1.0	15	30	2044	4071
1.5	15	0	2020	2577
1.5	15	20	2029	3161
1.5	15	30	2039	3841
2.0	15	0	2020	2577
2.0	15	20	2027	3089
2.0	15	30	2034	3611