1 Energy Information Administration, Monthly Energy Review, DOE/EIA-0035(2001/11) (Washington, DC, November 2001). Estimate for 2001 based on 17,090 gas wells completed in the first 10 months of 2001.

2 Energy Information Administration, Advance Summary: Crude Oil, Natural Gas, and Natural Gas Liquids Reserves: 2000 Annual Report, DOE/EIA-0216(2000)Advance Summary, p. 2, web site www.eia.gov/pub/oil_gas/natural_gas/data_publications/advanced_ summary_2000/adsum2000.pdf.

3 Energy Information Administration, Natural Gas Monthly, DOE/EIA-0130(2001/10) (Washington, DC, October 2001), Table 14, p. 26.

4 Projected values for 2001 and 2002 are from Energy Information Administration, Short-Term Energy Outlook (November 2001), web site www.eia.gov/emeu/steo/pub/contents.html.

5 Total natural gas reserve replacement for 2000 was 152 percent when new natural gas discoveries plus reserve adjustments, net reserve revisions, and net reserves from sales and acquisitions are considered. Only new wellhead gas discoveries are considered in this discussion, because the new reserves are a direct result of the natural gas found through drilling activity. In contrast, reserve revisions, for example, can represent the installation of recovery equipment, which was made more affordable by the high natural gas prices of 2000.

6 Energy Information Administration, Annual Energy Outlook 2002, DOE/EIA-0383(2002) (Washington, DC, December 2001), web site www.eia.gov/oiaf/aeo/.

7 Resources judged to be off limits because of the prohibitive effect of compliance with environmental laws and regulations.

8 Lease stipulations are mandated modifications to a lease.

9 Unproved resources are those resources that are estimated to exist based on analyses of the size and characteristics of existing fields and the geologic basins in which they reside, but these resources have not been proven to exist through actual drilling.

10 Technically recoverable resources are resources in accumulations producible using current recovery technology but without reference to economic profitability. These resources are generally conceived as existing in accumulations of sufficient size to be amenable to the application of existing recovery technology.

11 Undiscovered resources are unproved resources that are estimated to exist in fields that have yet to be discovered.

12 “Worldwide Look at Reserves and Production,” Oil & Gas Journal, Vol. 98, No. 51 (December 18, 2000), pp. 121-124.

13 Statistics on LNG trade are from D. Bamber, ed., Fundamentals of the Global LNG Industry (London, UK: Petroleum Economist, Ltd., March 2001), p. 11.

14 The correlation coefficient of these two data series is 0.898. However, the relatively low number of data points limits the ability to make an inference from this statistic.

15 The production half-life represents the amount of time that passes before a well (or a group of wells) produces natural gas at 50 percent of its (their) initial production level. The production rate half-life has declined for a host of reasons, including improvements in production technology and higher utilization of productive capacity.

16 Energy Information Administration, Office of Oil and Gas, Reserves and Production Division.