A group of scientists from the University of Houston has recently demonstrated that a non-toxic and low-cost nanofluid can be applied to efficiently recover even highly viscous heavy oil from reservoirs.
The nanofluid is produced in a normal household blender using sodium available in the market. In laboratory tests, the nanofluid helped recover 80% of extra-heavy oil that had a viscosity of over 400,000 centipoises at room temperatures.
According to Zhifeng Ren, director of the Texas Center for Superconductivity at the University of Houston and corresponding author of a study that explained the work, field recovery is anticipated to be below the 80% demonstrated in laboratory settings; but how much less will rely on the conditions of the oilfield.
Published in the Materials Today Physics journal, the study has proposed a new breakthrough in the application of nanotechnology to offer economical and environmentally sustainable means to generate oil.
The team observed that the supposed heavy oil—the outcome of the molecular structure of the oil—constitutes up to 70% of worldwide oil reserves, indicating that it will be required to fulfill the rising energy requirements until clean energy sources are completely developed.
Present-day extraction technologies involving the use of steam are not only costly but also damage the environment.
Ren, who is also the M.D. Anderson Chair Professor of Physics at the University of Houston, added that the nanofluid uses at least three mechanisms to recover oil from the reservoir:
- When the sodium nanoparticles make contact with water in the reservoir, a chemical reaction is created and heat is subsequently produced. This reaction works almost like steam flooding and other heat-based methods to drive oil from the reservoir, without the requirement for an external—and greenhouse gas-emitting—heat source.
- The nanofluid also triggers a reaction that produces sodium hydroxide—a chemical often used for alkaline flooding in oil fields. This sodium hydroxide can fuel movement in the oil and trigger a reaction that decreases viscosity.
- A third reaction generates hydrogen gas, which can be utilized for gas flooding—another standard method used to recover oil.
After the reaction, the sodium nanomaterials dissipate and therefore remove concerns relating to environmental damage. But Ren added that optimal concentrations will differ based on the conditions of individual reservoirs and he also observed that raising the level of the nanomaterial did not essentially result in higher oil recovery.
Ren worked with Dan Luo, the study’s co-author and postdoctoral researcher at the Texas Center for Superconductivity.
Based on these advantages, we anticipate that the sodium nanofluid could become a game-changing technology for recovery of oil of any viscosity, as well as a milestone in using nanotechnology to solve oil-recovery problems in the petroleum industry.
Sodium reacts readily with water, indicating that it might be handy to improve the recovery of oil, but that fact also complicated the preparation—if sodium is exposed too soon to the water in the reservoir, it would not provide the intended advantages.
To address this problem, the team prepared the sodium nanoparticles in silicone oil and allowed the sodium to disperse across the reservoir before it makes contact with water in the reservoir, setting off smaller chemical reactions over a greater region.
The sodium nanoparticles could also be dispersed in other solvents, such as kerosene and pentane, or they can even be combined with surfactants or polymers to obtain a higher rate of oil recovery.
Sodium also happens to be a light element, and this enabled the team to produce sodium nanoparticles inside the silicone oil, with the help of a kitchen blender.
Although the study focuses mainly on applying the nanofluid to improve the recovery of heavy oil, it could also be used in the production of light oil, and for more general household applications, such as clearing a grease-clogged pipe, Ren concluded.
Luo D & Ren Z (2020) Synthesis of Sodium Nanoparticles for Promising Extraction of Heavy Oil. Materials Today Physics. doi.org/10.1016/j.mtphys.2020.100276.