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Guide to understanding enhanced oil recovery

Enhanced oil recovery (EOR) refers to extraction techniques that increase the amount of oil recovered from fields.   Using EOR processes, up to 60 percent of a reservoir’s oil can be extracted, versus only about 10 to 20 percent using conventional methods.

One EOR method that is gaining popularity is carbon dioxide (CO2) injection.  The process works exactly like it sounds.  CO2 is injected into oil wells and “pushes” recoverable oil towards production wells.

Image courtesy of Energy.gov

One reason CO2 injection recovery is getting more attention recently is because of its potential to store carbon dioxide underground.  Carbon capture and storage (CCS) is a technology that is quickly being developed to stymie greenhouse gas emissions, but it is still difficult to economically implement.  Since CO2 is needed for enhanced oil recovery, there is now a market for captured carbon.  Naturally occurring carbon dioxide reserves are not as bountiful as oil wells, so CO2 is often in demand by oil companies using EOR techniques.

This scenario seems too good to be true, and it certainly isn’t quite this simple, but it is already happening.  In 2013 the Department of Energy (DOE) dedicated a carbon capture project in Port Arthur, Texas that transports carbon to nearby oil fields where it is used for EOR.  The term for carbon that is captured and then put to work for oil extraction has been coined by the DOE as carbon capture, utilization and storage, or CCUS.

The DOE summarizes the potential of this technology, saying:

… not only can Carbon Capture and Storage (CCS) technology help industry make fossil energy use cleaner, safer and more sustainable, it also shows promise as a method to extract more, hard-to-access and presently untapped fossil energy resources. By putting the captured carbon dioxide to use, Carbon Capture, Utilization and Storage (CCUS) provides an additional business and market case for companies to pursue the environmental benefits of CCS.

In theory, CCUS is a good compromise between fossil fuel hungry industries, and those concerned about climate change and greenhouse gases.

This brings up a possibility for carbon capture not often discussed; if oil is going to be extracted regardless, is it more economical, and environmentally friendly, to capture carbon emissions and essentially recycle the gas to use in EOR?  Oil is obviously a valuable commodity, so why not place a bigger price on CO2 used to extract it and create a market for sequestered carbon?  Once it is used to extract oil it is stored underground anyway, much like it would be if traditional CCS methods were used.  This effectively puts a price on carbon, which then makes capturing emissions less expensive, and even profitable.  This could even have implications for the EPA’s new rules on emissions created by coal-burning power plants.  Carbon capture technology will be required, but could that carbon then be sold to extract more energy?

The DOE estimates in a 2011 report that,

“[t]he market for captured CO2 emissions from power plants created by economically feasible CO2-EOR projects . . . would be sufficient to permanently store the CO2 emissions from 93 large one GW size coal-fired power plants operated for 30 years.”

So, enhanced oil recovery seems like the equivalent of fracking with CO2, which sounds like a bad idea.  But, if the CO2 is stored permanently underground and the net carbon output is negative, is this actually a step forward for emission reduction by power plants?  Renewable energy is gaining ground, but fossil fuels are definitely still dominating the energy mix.  Perhaps, instead of fighting against generation methods that emit CO2, we can put the CO2 to use instead.  If we do this right, it can be stored and we can prevent environmental damage.

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