Future Energy Systems researcher Juliana Leung is using subsurface engineering to find a social solution for our oil addiction
Modern society relies on energy. Whether you’re thinking globally, regionally, or in our personal lives, that’s a fact as solid as the ground we stand on. And that ground is where a lot of our energy comes from.
Whether coal, geothermal, or oil and gas, the Earth beneath our feet is an essential well of energy resources, but accessing them isn’t easy or straightforward. Harnessing energy sources under the ground can present major challenges because they’re hard to assess and even harder to access.
Future Energy Systems researcher Juliana Leung is studying these problems. A subsurface engineer – specializing in operations that occur below ground, where information, monitoring, and operations can only be observed or accessed with difficulty – Juliana leads her research group in analysing and improving the behaviour of deep oil well extraction processes. Her work focuses on balancing our society’s pressing need for energy and the equally important need to improve environmental performance in how we harvest that energy, all within systems that run out of sight deep underground.
“Ultimately, we want a green transition –– that can’t be argued” she says. “But in the meantime, we can’t just shut down oil and gas without a plan to replace them. So to be responsible we need to reduce the carbon footprint and we can do that by making things more efficient.”
Through innovations that make information and options more accessible to energy producers, Juliana and her group hope to improve our relationships with energy, for the good of our entire society.
A shifting social license
In 2015, the Government of Alberta found that 27.4 percent of its GDP was directly tied to the oil and gas industry, and in 2018, the Government of Canada found that the oil and gas sector contributed over $116 billion dollars to the national GDP. Much of this productivity is tied to the oil sands operations in northern Alberta. Despite recent and historic advances in renewable energy, the Canadian Government found that hydrocarbon-based energy sector is still the primary source of energy for consumers and industry.
The current energy system relies on hydrocarbons for many reasons, including the system-wide limitations of available infrastructure and grid operation, and practical considerations like the ease of their storage and transport. But feelings of discontent about the industry are also on the rise, both in general terms –– opinions about our society’s reliance on non-renewables –– and related to the specific ways that producers operate their sites.
Images of disturbed land and affected animals are some of the most immediately relatable touchstones people see, and public awareness of greenhouse gas measurements and the high use of water in extraction processes is also increasing. The balance of the environment versus oil conflict rests on a delicate fulcrum that Juliana believes cannot be ignored if the energy system is to remain able to operate and evolve. From her perspective it comes down to an issue of social license.
“The times are changing, what’s acceptable is changing,” she explains. The environmental concerns that arise from oil extraction are inescapable and can’t be brushed aside by the necessity of oil.
“Companies can only operate because the public allows it. If people start seeing the effects of the operations as intolerable, the oil companies lose that confidence and they will be forced to stop operating.”
The problem, she points out, is that our current system is still intrinsically tied to hydrocarbons, whether it directly supports a family livelihood or allows a household to turn on the lights and stay warm in winter.
“Losing their social license isn’t an option,” she says. “Companies need to adopt practices that improve the environmental outcomes, and minimize their impacts.”
Juliana hopes her research will help address that problem.
“The image people have of oil extraction is often those big open-pit mines. The truth is that only about twenty percent of the total oil reservoirs can be accessed that way,” she explains. “Most of the oil is too deep for that technique, so you need to be able to extract without mining.”
To operate these deep underground oil wells, companies typically rely on a process called steam-assisted gravity drainage (SAG-D). In this method, water is heated to steam and injected into the oil reservoir, which helps make the bitumen mixture less viscous and easier to transport out of the ground. Unfortunately, this process produces greenhouse gas emissions as natural gas is used to heat the water.
And that’s not the only concern: these processes can use millions of litres of water a day. The industry uses a specific metric to track this: a ratio of barrels of water converted into steam for use in SAG-D compared to how many barrels of oil are recovered by that steam. This steam-oil ratio measures the efficiency of the specific process, and can range from 2:1 to 5:1. The water used is contaminated with heavy oils and other components, requiring careful and painstaking purification for either recycling or release.
“Relying on large amounts of water like this isn’t sustainable,” Juliana says. “Instead, we focus on developing methods of extraction that use solvents instead.”
Modelling the changes
In Juliana’s field, the term ‘solvent’ can refer to any agent that can dissolve something else, in this case bitumen. Her team is primarily examining light hydrocarbons, specifically methane, or natural gas, mixed with carbon dioxide. Finding an alternative to pure steam that’s more efficient and more environmentally-friendly is the key, she points out, and there’s growing evidence that solvents could be a game-changer.
“It’s like trying to wash an oily plate. If you just use water, you can never get all the oil off the plate,” Juliana says. That’s because of phase differences –– the water and the oil repel each other. Including solvents or additives to the process can solve that.
“Using a solvent is like adding soap. Now you can wash the oil much more effectively off the plate,” she adds. “With the solvent, we can make the process a lot faster and easier.” In fact, given the better phase interactions, there’s even potential to get more oil out of reservoirs before they become economically unfeasible and have to be shut down.
But before the process can be adopted key questions must be answered: which dish soap is best, and what is the best dish-washing technique?
In Juliana’s lab, students are interested in examining different kinds of ‘soap’ –– additives and solvents –– for the oil extraction process, to see how they affect interphases –– the interactions between the oil in the reservoir and the extraction solution. This is considered next-generation or alternative technology for the oil industry.
When pursuing any new technology, however, there are always many questions to consider. With subsurface operations, the difficulties are compounded by the fact that you can’t directly observe the process or the underground environment, and have to rely on associated measurements and inferences from that data.
“We don’t know the shape of the reservoir, or where there might be aquifers that leech heat, make the process less efficient, or what other materials are down there,” Juliana explains. This is a problem, she says, because all these factors can have major effects on the efficiency of oil extraction. She adds: “We observe the flow of material leaving the well and make adjustments from that.”
The creation and refinement of well-structured oil well models is thus key to the work being conducted in Juliana’s lab. Students use artificial intelligence techniques, including machine learning, to train computers to simulate real-world effects of changing parameters of the oil extraction, including flow rates and the composition of the solvent injected in the well.
“We want this research to be used, so it’s important we keep focused on what’s realistic,” Juliana says.
The question of feasibility is always on her mind. The required change to oil well infrastructure required needs to be minimal. Chemicals and solvents considered for these applications need to be easily available, and it needs to be possible to separate them from the oil mixture and recycle them. Currently, her students are examining mixes of carbon dioxide and methane –– both very commonly available.
“But even with something as common as CO2 operators will ask ‘How do I get that?’, so we need to always be thinking about the implications and requirements,” she explains.
To solve these issues, her students work with a combination of simulated and real-life data. Ideally, their goal is simple: figure out how to extract more oil more quickly, while minimizing the number of wells to be drilled, and lowering the ratio of how much steam or solvent is needed per unit oil extracted.
This involves work down two distinct avenues. One is exploring how the relevant physics work at a very small scale –– for example, describing the mixing properties of the solvents and the various complex components that make up bitumen. This can predict how different mixes will act when injected, and what properties and additives aid or inhibit the process.
The other avenue is at a much larger scale: the actual reservoir dynamics and behaviours. Using techniques like machine learning can inform operators about better protocols for different situations, providing key insights into processes generally governed by very limited data.
Cooperation in practice and in research
When approaching these big problems, collaboration is key. For both lines of research, Juliana is collaborating with a number of researchers from different engineering departments, as well as from the University of Calgary, through two separate FES projects. In her view, involvement in FES has facilitated incredible collaboration opportunities among researchers to tackle these problems. Juliana’s team can focus on the modeling aspect of various research questions, using high-quality experimental data and knowledge gathered from her co-PIs, including Zhehui Jin, John Shaw, Japan Trivedi, Hongbo Zeng, Xuehua Zhang, and their students.
As much as Juliana is contributing to the development of solvent-based extraction technology, her lab’s research work isn’t solely focused on oil sands operation. Many processes, even within the energy field, rely on technologies deep in the ground, and for these, expertise like Juliana’s is key.
“Regardless of what you’re doing, whether it’s oil sands, shale gas, even geothermal energy, all the subsurface engineering in FES... we’re trying to put together teams of experts to solve the energy problems we have,” Juliana says. “It’s not just about oil, but all the available resources, and we need to work together to make sure we’re finding the best solutions.”
It is Juliana’s hope that this cooperation in the research lab will be reflected by cooperation with companies and the sector at large. So far, this hope is being realized.
Juliana has found that the oil sector's interest in green technologies is growing, with companies paying close attention to the research and results from labs like hers, and participating in the research. For example, her students use real data recorded from wells operated by their partner Cenovus Energy, which has implemented a company-wide goal to reach carbon neutrality in all their operations.
“Reaching net-zero carbon is a goal for the sector, but some companies are more willing to try solvents and commercialize new technologies than others,” Juliana says. She finds that it can be easier for the larger companies to lead this kind of experimental work, but it benefits everyone to adopt it.
Though the steam-based status quo would be cheaper, Juliana finds that companies and well operators are aware of the need to find eco-friendly measures, and are working to meet public expectations and keep their social license.
“The social pressure and the environmental pressure that prompts it –– those aren’t going away, and they shouldn’t,” she says. Solving the problem of the environmental impact and allowing the hydrocarbon sector to keep supporting the energy system throughout the green transition is her main goal.
“This isn’t just theoretical, or exploratory. We are finding ways to make this situation better for people and for our society,” she concludes.
“As an engineer, you should look for solutions that are practical and solve the problems we have. Everyone needs energy now, the question is: how do we get it?”