DEPLETION OF THE WORLD OIL RESERVES
Omar Campos
Ferreira
Energy Planning Course UFMG
English version: Frida Eidelman
The assessment of the amount of the world oil reserves is a question of strategic interest since oil is responsible for one third of all energy used in the world and for almost all fuel used in transportation.
Several attempts of assessment, using different
methodologies, were made and were frustrated perhaps due to
insufficient data. It should be noted that as data accumulates
the projections tend to converge. Recent examples of concurrent
projections are given in works presented by the World Energy
Council -WEC
( "Energy for Tomorrows World" , St.
Martins Press/1993) and by Petroconsultants ("An Oil
Depletion Model" - C.J.Campbell/1994). The former does not
give details about the methodology used for the projection and
informs that in 1990 he remnant reserve of "conventional
oil" (excluding, therefore, schist oil and bituminous sand )
was 57% of the total reserve. The latter uses an analysis method
of Fractal Geometry and concludes that around 1995 the remnant
was 50% of the total reserve.
In the present work we present our analysis of this question using the methodology of logistic function projection that was presented in the last issue of e & e, whose results are concurrent with both referred works.
The data base was extracted from the work of C.
J. Campbell and contains the necessary information for applying
the logistic function methodology: the known world reserve, year
by year, from 1930 on and the decennial average rate of new
fields discovered ( Table 1). The use of decennial average is
justifiable, considering the random character of discoveries, as
a way of smoothing the curves used in the projections, since de
differential equation of the logistic curve assumes the
continuity of the involved variable; the disadvantage is the loss
of resolution in the determination of the period in which the
rate reaches its maximum value.
Table 1 - Evolution of the world oil reserve |
||||||
Year |
1935 |
1945 |
1955 |
1965 |
1975 |
1985 |
Accumulated Discoveries Gb* (N) | 177,9 |
337,8 |
616,3 |
1.022,1 |
1.233,5 |
1.427,4 |
Average Discovery Rate Gb/year (dN/dt) | 13,2 |
20,6 |
28,0 |
34,5 |
23,9 |
12,0 |
ln F/(1=F)** | -2,006 |
-1,236 |
-0,3604 |
0,7602 |
1,532 |
2,979 |
* Gb = giga-barrel = 1 ´ 1012
barrel
** F = N/
The data treatment starts by studying the evolution of the accumulated reserve. For this first prospect, the value of the final reserve is any value, since it does not affect the nature of equation ln
Staring from the value of WECs study, we take = 1.500 Gb.. The adjustment of the data to the law ln F/(1-F) = at + b by linear regression gives for the correlation coefficient R2 = 0,9953, which demonstrates that the logistic function model is suitable for the interpretation (Fig.1). The perfect fit would correspond to R2 = 1,000.
Figure 1:
Accumulated world oil discoveries - Logistic curve fit
The second step would be to estimate by fitting the average discovery rate to the parabola. .
The fitted curve resulted in
The observed values are marked together with the fitted curve (Fig.2).
Figure 2 : Average Decennial of
Yearly Oil Discoveries
The methodology used indicates that the accumulated world reserves are 1,630 ´ 1012 barrels, equivalent to 220 ´ 1012 t. The projected evolution for the accumulated reserves is shown in Figure 3.
Figure 3: projected evolution
for the accumulated oil reserves
WECs study gives a value of 220 ´ 1012 t while that of Petroconsultants, 243 ´ 1012 t, which demonstrates the convergence of the independent projections. Taking the average value of the three projections for the total reserve, 222 ´ 10 12 t and considering that until 1996 103 ´ 12 t have been extracted and consumed, one concludes that the oil extraction will reach its maximum rate until the year 2 000.
What will come in the next century is a matter of speculation. Maybe it will not occur a new price shock as in the seventies because the world economy prepared itself for the new situation. Nevertheless, a gradual raise of prices is inevitable. In physical terms, the world energy income will decrease. The distribution of the burden will certainly penalize mainly the poorer countries.
The energy problem will be more serious in the transportation sector, since the industrial and domestic uses will be satisfied by the electricity produced by nuclear power plants, in spite of the world unwillingness to accept them.
For Brazil, it will be the opportunity for developing biomass energy due to the exceptional conditions of territorial extension, small population, tending to stabilize itself around 250 million inhabitants, and the edaphic-climatic characteristics of its territory. It would be also the case of moderating the adhesion to the global economy model or, at least, to carefully negotiate it.
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