Producing oil with negative CO2 emissions
Dr Furqan Hussain, from UNSW Petroleum Engineering, is concerned with one of humanity’s biggest conundrums: how to significantly reduce CO2 emissions (and lessen the likelihood of catastrophic climate change) while slowly weaning ourselves off fossil fuels.
Injecting carbon dioxide (CO2) into oil reservoirs to maximise oil recovery is not a new idea. In the US, for example, it has been a popular method for many decades. But, says Dr Furqan Hussain from UNSW Petroleum Engineering, over the past 10 years, and in the face of growing environmental awareness, the method focus has changed. It now shines with equal brightness on not only how much extra oil can be extracted but how much CO2 can be squirrelled away. This “CO2 sequestration” is a key focus of Hussain’s research.
“The petroleum industry is actively seeking to reduce the environmental impact of burning fossil fuels and this change in industry preferences has pushed many research groups in this direction,” Hussain says. “Now, CO2 injection projects are number one in terms of enhanced oil recovery projects in the US, with countries like China and Saudi Arabia following suit.”
We have two advantages here: firstly, we are storing CO2 in the subsurface formation, thus controlling CO2 concentration in the atmosphere. Secondly, we are producing oil that we can sell.
Dr Furqan Hussain, UNSW Petroleum Engineering
CO2 sequestration is about capturing CO2 emissions from the source, for example the industrial exhaust of a cement factory, then storing it long term so that it doesn’t go into the atmosphere and contribute to global warming and climate change. In the context of a petroleum reservoir, CO2 sequestration works because the CO2, when injected, remains in place while the oil is displaced.
“We have two advantages here: firstly, we are storing CO2 in the subsurface formation, thus controlling CO2 concentration in the atmosphere. Secondly, we are producing oil that we can sell,” Hussain says. “However, the main challenge we have at the moment is that CO2 is lighter than oil, so when it is injected into the reservoir it stays at the top and doesn’t displace oil from the lower areas. We call this a ‘sweep’, so currently we can say the sweep efficiency of CO2 is very low.
“Our research has focused on changing injection schemes to improve this CO2 sweep efficiency, and we have discovered a method to reduce the gravity effects of CO2 so it can go into lower parts of the reservoir. We have also discovered that this enhances the CO2 retention into the reservoir as well.”
Hussain’s research has attracted international attention. Last year, he was one of just 29 researchers from around the world invited to pitch a research proposal to Saudi Aramco, a national petroleum and natural gas company in Saudi Arabia. The event, called “RETiQuest”, was initiated by Saudi Aramco to unearth innovative research in economically and environmentally feasible hydrocarbon recovery, and Hussain is now working on the idea he took to that event. “I’ve also had quite a lot of interest from Sinopeca, a big oil company in China, which is very much interested in making more of its fields feasible for CO2 injection,” he says.
“We now have our preliminary results from synthetic oil and model rocks, so our next step is to do the experiments on more realistic rock and oil samples. Once we have that data I anticipate being able to commercialise this within the next five years.”
Hussain acknowledges that producing more oil through the method will, of course, lead to more CO2 when it is burned by industry, but he says this is necessary for the time being. “It will take some time for renewables and other sources of energy to become significant contributors to the energy mix; realistically, we will continue to need fossil fuels for a significant period of time. CO2 sequestration is important because it will reduce the impact of CO2 on the environment while these other energy sources come into their own.
“Interestingly and importantly, the methods we are developing could also be put to use in other ways. For example, injecting CO2 into a saline water aquifer. There is a lot of potential for CO2 sequestration around the world and, if we use all this potential, we could end up being able to store more CO2 than we produce.”
If you’re interested in learning more about Dr Furqan Hussain’s work, please contact him at: firstname.lastname@example.org