Sustainability 2011 , 3 2099
Energy Input/Energy Output which is the inverse of EROI. The results were inverted to provide EROI.
EROI and net energy are reported in Table 4 of Section 2.3. As an example, for 2002, the total cost
was $1.74 / GJ = $1.19 + $0.56. The energy invested was 42 MJ / GJ = $1.74 / GJ × 24 MJ/$.
The EROI of 24 = 1 GJ / 0.042 GJ (note the scale change of 42). And the net energy is
5.39 e^9 GJ = 5.63 e^9 − (0.042 × 5.63 e^9 GJ).
- Conclusions
This study has calculated the EROI and net energy of the Western Canadian petroleum and natural
gas production by a variety of methods and the results suggest several conclusions.
4.1. The Current State of Western Canadian Natural Gas and Oil Production
All of three methods show a downward trend in EROI during the last decade (Figure 10) and the
combined oil and gas industry has fallen from a long term high EROI of 79:1 (about 1% energy
consumed) to a low of 15:1 (7% energy consumed) (Figure 5).
Figure 10. EROI comparison according to technique.Natural gas EROI reached an even deeper low of 14:1 (7%) or even 13:1 (8%) with the NEB EUR
method. It is clear that state of the art conventional oil & natural gas extraction is unable to improve
drilling efficiency as fast as depletion is reducing well quality. The fact that EROI does not rebound
to match prior drilling rates and the EUR result shows no rebound indicates that well quality continues
0.005.0010.0015.0020.0025.0030.0035.000510152025303540451992 1994 1996 1998 2000 2002 2004 2006 2008 2010OilandGaswelldistancedrilled(1e6Meters)EnergyReturnedonEnergyInvestedOil & Gas Natural Gas Wells NEB EUR Estimate Meters Drilled