1. CO2 Enhanced Oil Recovery and Storage in Reservoirs
CHE384-Energy Technology and Policy
Xi Chen
Nov. 19th, 2007

2. EOR-Background Primary recovery Secondary recovery
Natural pressure, 10% OOIP
Secondary recovery
Injection of water or gas, 20-40% OOIP
Tertiary or enhanced oil recovery
Aiming at recovery of 30%-60% OOIP

3. Categories of EOR Thermal recovery Chemical injection
Steam flooding, ~50% of EOR production
Chemical injection
Polymer/water flooding, <1%
Gas injection ~50%
immiscible flooding: CH4, N2
miscible flooding : CO2
Process
Ult. Recovery
% OOIP
Utilization
Miscible
10-15
10 MCF/bbl
Immiscible
5-10
Lecture notes from
Dr. Larry W. Lake

4. EOR by CO2 flooding

5. Advantages of CO2 flooding
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
Naturally occuring source
Environmental benefit if industrial CO2 is used and stored in reservoirs
Capture and sequestration of CO2 from combustion of fossil fuel

6. Source: Oil & Gas Journal
206,000 barrels per day in 2004 = 4% of the Nation’s total.

7. 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

8. 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.

9. Technical challenge Poor sweep efficiency CO2 related problem
Gravity override
Mobility contrast
Reservoir heterogeneity
CO2 related problem
Corrosion on facilities
Solid deposition in reservoir formation
Well spacing
Greater spacing causes sweep efficiency reduction

10. CO2 mobility control Foam Thickening agent Chemical gels
mixed surfactants as foaming agent
Thickening agent
Fluorinated compound or polymer (good solubility in CO2)
Chemical gels
In-situ gelation of polymer to lower permeability

11. CO2 Storage in Reservoirs
Most favorable site for storage
Dense webs of seismic and well for long-term trap
Surface and subsurface infrastructure readily converted for CO2 distribution and injection
Less costly

12. CO2 Storage in Reservoirs
CO2 capacity of a reservoir:
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

13. Economics Cost of CO2 from different sources:
Naturally occuring CO2: $14/t
Pure anthropogenic CO2 from chemical plant: $18/t
Capture and processing of CO2 from coal fired plant: $18-54/t
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.
Lako, P. (2002) Options for CO2 Sequestration and Enhanced
Fuel Supply.

14. 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.

15. Questions?