CO2 Enhanced Oil Recovery and Storage in Reservoirs

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

2. EOR-Background • Primary 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 • Steam flooding, ~50% of EOR production • Chemical injection • Polymer/water flooding, <1% • Gas injection ~50% • immiscible flooding: CH4, N2 • miscible flooding : CO2 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. 537-546

8. Optimum reservoir parameters and weighting factorsfor 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 • 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 • 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?