Oil Depletion Calculator

In my article, "The Big Crunch" I mentioned writing a BASIC computer program to calculate world oil depletion time; from about starting year 2000 to some computed time in the future.
Due to oil industry reluctance to divulge oil reserve data an analyst must make assumptions based on existing available data. Adding up reported oil reserves I started the calculations at world oil reserves as being 1 trillion barrels (1000E9) and World oil consumption at 24 billion barrels (24E9). Oil depletion figures in the year 1999 indicated the depletion rate (reduction in discoveries) as being 2.5% (.025) and the increase in oil discoveries as starting out as 1 barrel discovered for every 4 consumed (.25). Oil consumption was rated as being 1.5% or .015.
The results of the computation is as follows; following is the computer program itself.

Year World Oil Reserves Total New Oil Discoveries, in barrels

1 981,640,000,000 11,850,000,000

5 903,027,811,285 33,823,607,750

10 792,962,591,153 58,338,868,719

15 699,458,159,217 79,939,159,578

20 532,062,426,110 98,971,082,829

25 380,218,620,253 115,740,028,441

30 213,265,490,335 130,515,074,202

35 30,436,537,394 143,533,303,392

36 -8,109,306,478 145,944,970,807



Depletion Program in BASIC (Should work in most BASIC versions)

I wrote this program on a Radio Shack Model 100.

100 Input "Todays Known Oil Reserves"; R
110 Input "Known World Oil consumption"; C
115 Let T=0
120 Let G=C *.25
125 Let T=G
130 For I=100
170 Let C=C+(C*.015)
180 Let R=R+G-C
190 Let G=G-(G*.025)
192 Let T=T+G
195 Print "World Reserves= ";R
197 Print "Growth in World Reserves";T
200 Print "Years ="; I
210 Stop
220 Next I
500 End


Instructions:
1) Type in at prompt known reserves ( I used 1000E9)
2) Type in at prompt oil consumption per year ( I used 24E9).
3) After calculation computer halts and shows results per year on screen: type cont to continue.

With my figures oil is depleted after year 35 and shows a negative figure for year 36. Oil discovers total over 143 billion barrels. When you consider that the most optimistic figure for oil in ANWAR as being 16 billion barrels these figures are illuminating.
This program may appear simple but it calculates a number of positive growing variables and negative declining figures and correcting them against each other to come up with the corrected results.