Geoscience Reference
In-Depth Information
located near industrial sources of CO
2
. Costs to construct pipelines to connect
sources of CO
2
with oil and gas fields may, in part, determine whether an EOR
operation using industrial sources of CO
2
is feasible.
Although the United States injects nearly 50 MtCO
2
underground each
year for the purposes of EOR, that amount represents approximately 2% of the
CO
2
emitted from fossil fuel electricity generation alone. The sheer volume of
CO
2
envisioned for CCS as a climate mitigation option is overwhelming
compared to the amount of CO
2
used for EOR. It may be that EOR will
increase in the future, depending on economic, regulatory, and technical
factors, and more CO
2
will be sequestered as a consequence. It is also likely
that EOR would only account for a small fraction of the total amount of CO
2
injected underground in the future, even if CCS becomes a significant
component in an overall scheme to substantially reduce CO
2
emissions to the
atmosphere.
The In Salah and Weyburn Projects
The In Salah Project in Algeria is the world's first large-scale effort to
store CO
2
in a natural gas reservoir.
17
At In Salah, CO
2
is separated from the
produced natural gas (the gas contains approximately 5.5% CO
2
) and then
reinjected into the same formation. Approximately 17 MtCO
2
are planned to be
captured and stored over the lifetime of the project at a rate of slightly more
than 1 Mt per year.
18
The Weyburn Project in south-central Canada uses CO
2
produced from a
coal gasification plant in North Dakota for EOR, injecting up to 5,000 tCO
2
per day into the formation and recovering oil.
19
Approximately 20 MtCO
2
are
expected to remain in the formation over the lifetime of the project.
20
Deep Saline Reservoirs
Some rocks in sedimentary basins contain saline fluids—brines or
brackish water unsuitable for agriculture or drinking. As with oil and gas, deep
saline reservoirs can be found onshore and offshore; in fact, they are often part
of oil and gas reservoirs and share many characteristics. The oil industry
routinely injects brines recovered during oil production into saline reservoirs
for disposal.
21
Using suitably deep saline reservoirs for CO
2
sequestration has
advantages: (1) they are more widespread in the United States than oil and gas
reservoirs and thus have greater probability of being close to large point
