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Sustainability 2011 , 3 2091

Table 4. Total cost per GJ, Net EUR and EROI for natural gas wells.

Year

Total Cost

$(U.S. 2002)

per GJ

Invested Energy per

GJ via 24 MJ/$(U.S.

2002) in MJ

Net Estimated

Ultimate Recovery

(1 e^9 GJ)

EROI

1996 $1.13 27 4.79 37

1997 $1.26 30 5.72 33

1998 $1.32 32 5.74 31

1999 $1.28 31 5.44 33

2000 $1.57 38 5.83 27

2001 $1.82 44 6.18 23

2002 $1.74 42 5.39 24

2003 $1.95 47 5.88 21

2004 $2.17 52 6.42 19

2005 $2.86 69 5.57 15

2006 $2.97 71 5.97 14

2007 $3.01 72 4.41 14

2008 $3.24 78 4.09 13

Figure 8. EROI using NEB estimates of ultimate recovery, with meters drilled.

The EROI curve in Figure 8 is slightly less volatile than the rolling average technique, but more
strikingly, the years 2007 and 2008 do not show the rebound in EROI that the rolling average method
displayed. Assuming the NEB estimates for EUR are correct, this result indicates that the rebound was

0

2

4

6

8

10

12

14

16

18

20

0

5

10

15

20

25

30

35

40

1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

Distance

Drilled

(1e6

Meters)

Energy

Returned

on

Energy

Invested

Natural Gas Well EROI EROI via NEB Estimated Recovery

Gas Intent Meters Drilled

G