DISCUSSION AND COMPARISON OF RESULTS WITH THE PREVIOUS

                    
USGS/MMS ASSESSMENT

                              
Gas


     The technically recoverable conventional resources of natural gas 
from both growth of reserves in existing fields and from undiscovered
accumulations onshore and in State waters, as of this assessment, is
approximately 580 TCFG, compared with 347 TCFG at the time of the
previous National Assessment (1989). Proved reserves of natural gas in
the United States stand at approximately 135 TCFG, compared to 157 TCFG
in 1989. Natural gas annual production has increased significantly in
the intervening years from 17.0 TCFG in 1989 to about 17.8 TCFG in
1993.

     Estimated mean amounts of undiscovered technically recoverable
conventional gas resources onshore and in State waters are
approximately the same as those reported in the previous National
Assessment (Mast and others, 1989) (259 vs. 254 TCFG, respectively).
Although estimates of conventional natural gas have actually been
reduced in a few significant areas, such as the Anadarko Basin,
estimates have been raised in a number of others (table 2). The overall
change probably reflects the discovery of about 26 TCFG during the past
7 years and movement of certain resources previously estimated under
conventional categories to plays in continuous-type deposits for this
assessment.

     Estimates of future growth of gas reserves in known fields are 
up significantly for this assessment, having increased from 93 TCFG in
1989 to approximately 322 TCFG for this assessment. As with oil, this
increase reflects, more than anything else, the use of the EIA OGIFF
data set rather than American Petroleum Institute-American Gas
Association data.

     In addition to conventional gas resources, the USGS has, for 
the first time, made a systematic assessment of potential additions to
technically recoverable resources deriving from continuous-type,
largely unconventional, reservoirs of natural gas. Resources in this
category were not evaluated in the previous assessment (Mast and
others, 1989) because of the difficulties in developing adequate
methodologies and data. Historically, these resources have contributed
little to the national energy supply. However, we estimate there
exists, at a mean value, 308 TCFG of technically recoverable natural
gas in continuous-type deposits in sandstones, shales, and chalks, and
almost 50 TCFG of technically recoverable gas in coal-bed deposits.
These resources are thus comparable in magnitude to conventional
resources, although their anticipated deliverability and development
economics will be very different than gas in conventional
accumulations.

     The 1995 National Assessment documents large, technically 
recoverable resources of non-associated gas in continuous-type deposits.
Significant extraction effort will be required to obtain this gas.
Based on existing technology, the assessment indicates that
approximately 960,000 productive wells will be required to recover
potential reserve additions of 300 TCFG, based on the distribution of
EUR's shown in figure 13. Furthermore, extrapolation of present-day 
success ratios implies that roughly 570,000 "dry" holes would have to
be drilled along with the productive wells. By way of perspective, the
most oil and gas wells of all kinds drilled in the United States in 1
year is about 92,000, and from 1986 to the present the total has been
less than 40,000 wells per year. In the case of discrete (conventional)
fields, most resources have been recovered from relatively few, large
fields. Analogously, in the case of continuous-type gas accumulations,
most gas is expected to be recovered from a relatively small subset of
productive wells. The assessment data show that one-half of the mean
potential recoverable resources of 300 TCFG will be produced by about
100,000 wells, 25 percent will be produced by an additional 150,000
wells, and the remaining 25 percent will require some 700,000 producing
wells fig. 13).

Note: Table 2 was subdivided into various Regions:


Table2a contains Regions 1 & 2

Table2b contains Regions 3 & 4

Table2c contains Regions 5, 6 & 7

Table2d contains Region 8