Researchers from the Colorado School of Mines and ORNL used neutrons to visualize oil flow patterns during an enhanced recovery technique known as CO2 huff-n-puff. Credit: Duncan Harryman/ORNL, U.S. Dept. of Energy
Research using neutrons at Oak Ridge National Laboratory's High Flux Isotope Reactor is helping scientists better understand how to extract oil from unconventional reservoirs, serving to reinforce America's energy independence.
Dina Hegazy, a Colorado School of Mines researcher, is using neutrons at the High Flux Isotope Reactor (HFIR), one of the most powerful reactor-based neutron sources in the world, to increase the amount of oil recovered from hard-to-reach places. Hegazy's timely research arises amid historically low levels for America's Strategic Petroleum Reserve, the world's largest supply of emergency crude oil.
The focus of the research is the performance of an enhanced oil recovery (EOR) technique, known as CO2 huff-n-puff, in unconventional reservoirs. In unconventional reservoirs, oil is too tightly bound to rock for other extraction techniques, such as drilling, which leave behind up to two-thirds of the original oil. CO2 huff-n-puff has been shown to significantly improve oil recovery in these reservoirs compared to other EOR techniques. However, despite its success, EOR's operational parameters, such as injection pressure and huff duration, are low. Neutrons are helping to solve this problem and reinforce United States energy security.
"Neutrons gives us insight into these reservoirs that otherwise isn't possible," said James Torres, an instrument scientist at HFIR who assisted Hegazy with her experiment. "Neutrons help visualize fluid movement at a level of detail that enhances our understanding of oil recovery processes because they interact strongly with light elements, such as hydrogen."
Hegazy's research will be used to advance reservoir-scale computer simulations to help industry maximize the amount of oil collected using CO2-EOR, such as the CO2 huff-n-puff technique. Using HFIR's Multimodal Advanced Radiography Station (MARS), an instrument that performs radiography and computed tomography, Hegazy will continue working with the MARS team investigating nanoscale flow exchange between CO2 and various fluids in different shale samples.
"The goal is to look at how CO2 flows in nanopores that have oil in them," said Hegazy. "Understanding how the size of the nanopores affects the flow of CO2 gives us a better idea about how the flow displaces the oil and therefore increases the recovery rate."
In a completely oil-saturated shale sample, an image will appear dark at first glance. But as the CO2 begins to displace oil from the shale, the image becomes lighter, creating a contrast that allows Hegazy and her team to see the pattern of CO2 flow.
Thanks to one of the unique properties of neutrons, the sensitivity of neutrons to light elements, neutron imaging allows the team to visualize the movement of fluids within the shale samples. Also, neutrons are able to penetrate the shale samples more effectively at higher pressures.
"Working with the MARS team has been amazing," said Hegazy. "Everyone is very cooperative and open to exchanging ideas. And it is always an exciting privilege to see what's new at HFIR first-hand."
In addition to HFIR, ORNL has a second neutron source, the Spallation Neutron Source (SNS), which produces neutrons with an accelerator-based system and, like HFIR, brings researchers to ORNL from around the globe to conduct neutron scattering research.
SNS and HFIR, DOE Office of Science user facilities, enable scientists to employ the unique properties of neutrons to advance scientific discovery and address some of the most pressing challenges of our time.
Neutron scattering is used in many industries - including automotive, aerospace, steel, defense, industrial materials, energy storage, data storage and biomedicine - to address the 21st century's major scientific challenges.
Many discoveries are fueled by neutron research at ORNL, helping scientists answer big science questions and spur countless innovations such as stronger glass for mobile devices, more effective drug treatments, more reliable aircraft and rocket engines, cars with better gas mileage, improved armor for the military and batteries that are safer, charge faster and last longer.
UT-Battelle manages ORNL for DOE's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science. - Kaeli Dickert
