Oil and Gas at Your Door? (2005 Edition) - Earthworks

TERMS AND CONCEPTS
When natural gas is produced from oil wells it is called associated gas, while natural gas and
condensate wells produce nonassociated gas. Approximately 35% of natural gas recovered in
the U.S. is associated with oil recovery. 26
Sour gas is a highly undesirable type of gas to have produced near your property. 27 It contains
high concentrations of hydrogen sulfide (H 2 S), which is toxic, potentially fatal at certain concentrations,
and has a vile odor, much like rotten eggs. If H 2 S dissolves in water, it forms a mild
acid that can corrode pipes, valves, meters and other gas handling equipment. Sour gas is commonly
found in deep, hot, high pressure natural gas deposits such as the foothills of the Rocky
Mountains in Alberta and northeastern British Columbia. In the United States, some production
of sour gas occurs in Michigan and Texas. H 2 S may also be associated with coalbed methane
extraction. In Colorado and New Mexico, there have been numerous complaints related to H 2 S
contamination of water wells and migration into homes following coalbed methane development.
28 (For more information on sour gas, see the section on Impacts Associated with Oil and
Gas Operations.)
Not surprisingly, the oil and gas industry has focused most of its attention on the deposits that
are the easiest to find and extract, e.g., those in relatively shallow, highly porous rock formations.
These are known as conventional accumulations, and they tend to exist in localized
deposits. Nonconventional (also known as unconventional) oil and gas deposits tend to occur
over large geographic areas rather than in localized accumulations.
Historically, it was not possible to develop nonconventional deposits since the technology to do so
did not exist, or it was much too expensive to access and process the oil and gas. Over the past
two decades, however, improvements in technology have occurred largely as a result of government
subsidies. As a result, nonconventional gas deposits have become a noticeable source of
total U.S. domestic production.
The U.S. Energy Information Administration (EIA) predicts that natural gas production from nonconventional
sources (tight sands, shale, and coalbed methane) is going to increase more rapidly
than conventional production in the U.S. The EIA predictions show nonconventional gas production
from the lower 48 states growing from 6.6 trillion cubic feet (tcf) in 2003 (35% of natural gas
production in lower 48) to 8.6 tcf in 2025 (44% of lower 48 natural gas production). Industry
experts expect a much faster growth
in nonconventional gas production,
predicting that more than 10 tcf will
be produced in 2005. 29
10
8
History
Projections
Lower 48 NA
unconventional
This guide focuses primarily on the
development of conventional oil and
gas deposits. Recognizing, however,
that development of nonconventional
resources is on the rise, Chapter 1
includes a section on Development of
Nonconventional Oil and Gas.
6
4
2
Lower 48 AD
Alaska
0
1990 1995 2003 2010 2015 2020 2025
Lower 48 NA
conventional
onshore
Lower 48 NA
offshore
FIGURE I-1. NATURAL GAS PRODUCTION (CONVENTIONAL VS.
UNCONVENTIONAL), 1990-2025. Note: AD stands for gas that is
associated (dissolved) with crude oil production. Energy Information
Administration. 29a
I-3