Environmental Engineering Reference
In-Depth Information
depleted oil or gas reservoirs because these reservoirs have effective seals
that prevented the escape of hydrocarbons for thousands of years. Thus the
risks of losing stored natural gas are minimal (Benson et al., 2002).
However, depleted hydrocarbon fields in areas where natural gas storage
fields are required are insufficient. The same is also is true for CO
2
seques-
tration where sites are needed in the industrial and highly populated areas,
where depleted oil and gas fields are rare or nonexistent. The gas industry
has overcome this obstacle in part by creating storage fields in aquifers, and
this technique is an obvious choice for sequestration of carbon dioxide in
many industrial and highly populated regions around the world.
Storage of natural gas in aquifers is the process of injecting gas into an
aquifer of high or reasonably high permeability under structural conditions
that mimic natural oil and gas reservoirs, for example, anticline highs or up-
dip pinch-outs. In addition, a target aquifer must be free of faults so that the
stored gas will not escape through fault planes.
The keys to the success of storing natural gas and/or carbon dioxide in geo-
logic formations are site selection and accurate delineation of the host forma-
tion to ensure that the formations are continuous and extend over a wide area
without faults or other discontinuities that would allow escape of the injected
gas. A storage zone must be contained below impermeable overlying beds,
preferably structurally undisturbed, and laterally continuous to store large
quantities of gas to be injected continuously over a very long period. In addi-
tion, for any method of gas storage or carbon sequestration to have value, a reli-
able monitoring procedure must ensure that the process follows the projected
path. Monitoring must also implement early remedial action when required.
A number of technologies developed by the gas storage industry in the
United States and Europe have potential application to CO
2
sequestration.
Table 8.3 identifies those technologies.
Successful CO
2
sequestration requires participation by many disciplines.
The technology developed by the underground gas storage industry will
have significant application to CO
2
sequestration. Gas storage operators
have developed a technology portfolio that is not widely known or gener-
ally available across the E&P industry. The availability of this technology
and increasing the awareness of these possibilities could prevent duplica-
tion of effort, resulting in considerable savings and providing more effective
CO
2
sequestration (see Figure 8.8).
The gas storage industry has successfully operated storage fields for over
90 years and has developed a number of procedures and technologies that
can directly assist with the sequestration of CO
2
. Many of the technologies
utilized by gas storage operators were developed by and adopted from the
oil and gas industries.
Several technologies and procedures have been developed by the gas stor-
age industry directly to meet customer needs. This is especially true in the
area of aquifer gas storage which includes a portfolio of technologies unique
to the aquifer storage business. All the existing gas storage technology can
