CO2 Enhanced Oil Recovery
and Storage in Reservoirs
CHE384-Energy Technology and Policy
Xi Chen
Nov. 19th, 2007
EOR-Background
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Primary recovery
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Secondary recovery
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Natural pressure, 10% OOIP
Injection of water or gas, 20-40% OOIP
Tertiary or enhanced oil recovery

Aiming at recovery of 30%-60% OOIP
Categories of EOR

Thermal recovery

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Chemical injection

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Steam flooding, ~50% of EOR production
Polymer/water flooding, <1%
Gas injection
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~50%
immiscible flooding: CH4, N2
miscible flooding : CO2
Process
Ult. Recovery
% OOIP
Utilization
Miscible
10-15
10 MCF/bbl
Immiscible
5-10
10 MCF/bbl
Lecture notes
from
Dr. Larry W. Lake
EOR by CO2 flooding
Advantages of CO2 flooding

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Dense fluid over much of the range of
pressure and temperature in reservoirs
Low MMP (minimum miscibility pressure) and
high miscibility with oil
Low mutual solubility with water
Low cost and abundance

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Naturally occuring source
Environmental benefit if industrial CO2 is
used and stored in reservoirs

Capture and sequestration of CO2 from
combustion of fossil fuel
Source: Oil & Gas Journal
206,000 barrels per day in 2004 = 4% of the Nation’s total.
Screening criteria for application
of CO2 miscible flood
Gozalpour, “CO2 EOR and Storage in Oil Reservoirs”, 2005,
Oil & Gas Science and Technology – Rev. IFP,
Vol. 60 (2005), No. 3, pp. 537-546
Optimum reservoir parameters and weighting factors
for ranking oil reservoirs suitable for CO2 EOR
Rivas, O. et al. (1992) Ranking Reservoirs for Carbon Dioxide
Flooding Processes.
Technical challenge

Poor sweep efficiency

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CO2 related problem
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Gravity override
Mobility contrast
Reservoir heterogeneity
Corrosion on facilities
Solid deposition in reservoir formation
Well spacing

Greater spacing causes sweep efficiency reduction
CO2 mobility control
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Foam
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Thickening agent

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mixed surfactants as foaming agent
Fluorinated compound or polymer (good
solubility in CO2)
Chemical gels

In-situ gelation of polymer to lower
permeability
CO2 Storage in Reservoirs

Most favorable site for storage

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Dense webs of seismic and well for longterm trap
Surface and subsurface infrastructure
readily converted for CO2 distribution and
injection
Less costly
CO2 Storage in Reservoirs

CO2 capacity of a reservoir:

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Theoretically, equal to the volume
previously occupied by the produced oil
and water
Other factor: Water invasion, gravity
segregation, reservoir heterogeneity and
CO2 dissolution
Reservoir type, depth, size and safety of
CO2 storage
Economics

Cost of CO2 from different sources:
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Naturally occuring CO2: $14/t
Pure anthropogenic CO2 from chemical plant: $18/t
Capture and processing of CO2 from coal fired plant: $1854/t Lako, P. (2002) Options for CO2 Sequestration and Enhanced
Fuel Supply.
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CO2 utilization efficiency: 4~8 Mscf/bbl
(0.2~0.5t/bbl)
Transportation cost: $0.5~1.2/Mscf
Operation cost: $2-3/bbl
Economical even at a oil price of $40/bbl.
CO2 storage credit ($2.5/Mscf) makes it more
economical for producers.
Summary

Combination of CO2 EOR and storage in
reservoirs provides a bridge between
reducing greenhouse gases from industrial
waste streams and the beneficial use of CO2
injection for increasing oil and gas recovery.