Non-thermal Heavy Oil Recovery Table 2: Non-thermal Enhanced Heavy Oil Recovery Projects
2008 Non-thermal heavy oil enhanced oil recovery in the US, (˚API <26, Depth [ft] >2000) Type
Operator CO2 miscible CO2 immiscible
Chaparral Energy Denbury Denbury
Hydrocarbon miscible
BP Alaska BP Alaska BP Alaska BP Alaska BP Alaska
ConocoPhillips Hydrocarbon immiscible BP Alaska Nitrogen immiscible
ExxonMobil ExxonMobil Occidental
Polymer Figure 3: Trends in Thermal and Non-thermal Heavy Oil (<26oAPI) Recovery
10 15 20 25
-5 0 5
10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000
01998 Total 2000 2002 Gas injection 2004 Thermal 2006 2008 Improved waterflooding
driving fluids. When the injected gas contacts residual oil in place, the intermediates are dissolved in the oil at the gas-oil interface. Continued injection leads to multiple contacts with the oil which promotes the condensing gas drive mechanism and creates a mixing zone of oil recovery between the gas slug and oil bank.
Table 2 also shows a current trend in the US towards the application
of non-hydrocarbon gases e.g. CO2 and N2 as the injection fluid. The latter are typically not soluble in heavy crude oils. They can, however, become and maintain a dynamic miscibility with the reservoir oil through a combination of multiple-contact condensing-
and vaporising-gas drive mechanisms. With CO2, the mass transfer mechanisms could take place in a sequential manner inside the
CO2-oil mixing zone such that the leading edge of the mixing zone is dominated by CO2 condensation into the oil phase – which swells the oil and reduces its viscosity – whereas further upstream portion of the zone experiences oil vaporisation. Unlike gases such as
42 Depth [ft] > 2000
10 15 20 25
-5 0 5
10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000
01998 Total 2000 2002 Gas injection 2004 Thermal 2006 2008 Improved waterflooding
methane or propane, CO2 is uniquely able to extract heavy hydrocarbons, C5–C30, from reservoir oils. This allows CO2 to be applicable to both light and heavy oils. In addition to its ability to extract heavy hydrocarbons,
CO2 has other advantages such as a density comparable to reservoir oils, a low minimum miscibility pressure, and a positive impact on the
environment – through CO2 sequestration – by reducing greenhouse gas emissions. N2, flue gas (about 87 % N2 and 12 % CO2) and air can also be used as the injection gas; however, from the miscibility
point of view, the process requires somewhat higher injection pressures and it is limited to lighter oil reservoirs.
Can Horizontal Wells Impact Non-thermal Heavy Oil Recovery?
VAPEX process uses a mixture of propane and butane (as vaporising solvent) and of a non-condensable gas, e.g., natural gas or methane,
EXPLORATION & PRODUCTION – VOLUME 9 ISSUE 2 Depth [ft] > 2000
Tex. Tex.
Calif.
16 24 25
4800 4800 2500
Alas. 22 7000
Alas. Alas. Alas. Alas. Alas. Alas.
26 24
24–28 15–23 15–23 24
8800 6700 6600 4500 4900 6000
Okla. Miss. Miss.
19 22 11
5400 5050 8500
State Gravity oAPI Depth (ft) Enh Prod. (b/d) No of Projects
00 3070 70
3000 0
40500 1200 2600 3700 0
33000 3200 3200 9000 1000 3000 5000
6 3
1 3
00
US heavy oil EOR production [b/d]
US heavy oil EOR projects
US heavy oil EOR production [b/d]
US heavy oil EOR projects
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