American Oil and Gas Reporter - September 2018 - 95

SpecialReport: Reservoir Modeling & EUR

Carbon Capture Boosting Oil Recovery
shore LLC are expanding EOR operations
already to capitalize on the use of these
new anthropogenic CO2 sources as they
become available.

By J. Greg Schnacke,
John Harju
John Hamling,
James Sorensen
and Neil Wildgust

CO2 EOR
CO2 EOR is a proven process that
produces significant incremental oil and-
inherent to the production process-results
in safe, secure, long-term geologic storage
of CO2 in legacy hydrocarbon reservoirs.
CO2 EOR projects are driven by the
economic benefit of producing oil that
cannot be recovered commercially through
primary and secondary (i.e., waterflood)
production methods. CO2 EOR is most
commonly applied during the tertiary
production phase of producing conventional oil reservoirs (i.e., after the reservoir
has been depleted economically utilizing
primary and secondary recovery).
CO2 EOR projects are initiated when
the relative value of increased reserves
and incremental hydrocarbon production
exceeds the costs of acquiring the CO2,
and installing and operating the associated
infrastructure for a commercial project.
This value proposition is improving
steadily in the United States, which had
136 active commercial CO2 EOR projects
as of 2014, with predictions of strong
future growth.
Implementing CO2 EOR can extend
the life of oil fields where the financial,

PLANO, TX.-Chevron Corp. initiated
the first large-scale enhanced oil recovery
project in the world to use carbon dioxide
as the working fluid in 1972 in the Texas
Permian Basin. Four decades later in
2013, CO 2 EOR contributed nearly
280,000 barrels a day of U.S. oil production from more than 100 sites. The U.S.
Energy Information Administration reports
that by 2017, U.S. CO2 EOR production
had grown to 300,000 bbl/d.
In 2010, approximately 22 percent of
the CO2 used in U.S. EOR operations
was obtained from industrial sources.
Additional EOR projects initiated since
2013 in Montana, Wyoming and Texas
that also use captured CO2 confirm that
the supply of anthropogenic CO2 is growing and suggests an increasing proportion
in the total supply of CO2 for EOR.
The potential to deploy carbon capture
technology at greater scale across power
generation and other industrial sectors
may provide an opportunity to proliferate
both the number and geographical distribution of CO2 EOR operations, which
could boost domestic oil production. Several oil producers such as Denbury On-

public policy and environmental commitments to produce energy already have
been made. Fields where such commitments have been in place historically
may have reduced risk and uncertainty
with respect to gaining corporate and
regulatory authority going forward.
In many circumstances, these legacy
fields correspond with significant technical
knowledge bases that improve confidence
in the assessment of CO2 EOR project
viability and performance. Likewise, this
knowledge base can reduce operational
risk and inform management once projects
are under way.
Associated Carbon Storage
During CO2 EOR, injected CO2 swells
and mobilizes oil not recovered through
primary and secondary processes. Some
of the injected CO2 is produced along
with the newly mobilized oil. The produced CO2 is separated from the oil and
water, dehydrated, compressed, combined
with new CO2 being supplied to the field,
and subsequently reinjected as part of
the EOR process (Figure 1).
Studies show that virtually all the CO2
supplied to (or purchased for) an EOR
project remains safely and securely stored
within the geologic formation. Using anthropogenic CO2 for enhanced oil recovery,
such as from a coal-fired power plant, is
considered a form of carbon capture, uti-

FIGURE 1
EERC CG51515, AI

Purchased
Gas Composition

Purchased
Gas Stream

Custody
Transfer Meter
Volume Rate

180,000

Recycling
Facility

160,000

Oil and Gas
Production
Rates

Commingled
Gas Injection
Rate

Cumulative CO2 Volume

Produced/
Recycled Gas
Composition

140,000

100,000

60,000
40,000
Associated CO2 Storage

ay
Ju 13
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vJa 13
nM 14
ar
M -14
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-1
Ju 4
l
Se -14
pNo 14
vJa 14
nM 15
ar
M -15
ay
Ju 15
lSe 15
pNo 15
vJa 15
nM 16
ar
M -16
ay
-1
Ju 6
lSe 16
pNo 16
vJa 16
nM 17
ar
M -17
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-1
Ju 7
lSe 17
pNo 17
v17

Injection
Well

Gas
Storage

CO2 Recycled

80,000

20,000

Produced
Gas

Source: Denbury, MBOG

120,000

Reservoir
Production
Well

Injection (MMcf)
Purchase (MMcf)

Commingled Purchased/
Recycled Gas

Produced/Recycled
Gas Stream

Produced/Recycled Gas Stream

This process ﬂow diagram and cumulative carbon dioxide injection plot illustrates the movement of CO2 storage occurring in
association with Denbury Resources' commercial enhanced oil recovery process at the Bell Creek oil ﬁeld in southeastern Montana.

SEPTEMBER 2018 95

American Oil and Gas Reporter - September 2018

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