October 31, 1975 - Gerald R. Ford Presidential Library and Museum

Table 8--COMPARISON OF OPERATORS SURVEY AND FIELD STUDIES
Indicated Secondary and
Proved Reserves Tertiarl Reserves
Crude Oil Natural Gas Crude Oil Natural Gas
(MMBbls) (BCF) (MMBbl s) (BCF)
Operators Survey 19,891 67,485 1,469 211
Major Field Studies 19,416 68,300 1,479 377
Difference as a
percent of Field
Studies Estimates 2.4% 1.2% 0.7% 44.0%
The totals above are for 60 different field entities. The San
Juan Basin gas fields are considered to be two separate fields. Although
the comparisons for proved reserves are very close, an exami·nation of
the individual field proved reserves points up considerable differences,
as Tables 9 and 10 indicate. The very close comparison in the case of
indicated secondary and tertiary reserves of crude oil is coincidental.
The Operators Survey lists such reserves for 37 fields; the Field
Studies list such reserves for 18 fields; only 15 fields have these
reserves on both lists. The natural gas reserves in the indicated
secondary and tertiary category are too small for meaningful statistical
comparison.
Tabl e 9--Cor·1PARISON OF CRUDE OIL RESERVES,
OPERATORS SURVEY VERSUS MP,JOR FIEL[l STUfHES
Survey Est. as a
Percent of Field No. of Field Studies Reserves Survey Reserves
Studies Est. Fields (t+1Bbls} (MMBb1s}­
Under 50% 3
50% - 79% 5
80% - 89% 5
90% - 99% 13
100% - 109% 16
110% - 119% 3
120% - 149% 7
150% and over 8
Total 60
24
776.3
1 ,106.5
1,431. 7
1,439.9
12,087.6
1,058.8
1,092.3
422.4
19,415.5
337.6
655.6
1,181.5
1,338.4
12,928.6
1 ,188. 1
1,422.5
838.3
19,890.6