Researchers at the University of Houston have demonstrated that inexpensive and non-toxic nanofluids can be used to efficiently recover even heavy, highly viscous oils from formations. They talked about their research in an article for Materials Today Physics magazine.
The researchers explain that so-called heavy oil – the result of the molecular structure of oil – accounts for 70% of the world’s oil reserves and will be needed to meet growing energy demands until clean energy sources are developed and used everywhere. Modern technologies for oil extraction using steam are expensive and damage the environment.
However, scientists have developed a nanofluid that helps extract oil from the reservoir using three mechanisms:
The chemical reaction that occurs when sodium nanoparticles come into contact with water in a reservoir generates heat, acting in the same way as steam injection and other heat-based methods to push oil out of the reservoir, without the need for external – and greenhouse gas production – heat source.
The nanofluid also reacts to form sodium hydroxide, a chemical commonly used for alkaline flooding in oil fields. Sodium hydroxide can cause movement in the oil and cause a viscosity-lowering reaction.
The third reaction produces hydrogen gas that can be used for waterflooding, another common oil recovery method.
Sodium nanomaterials are dispersed after the reaction, thus not harming the environment. Optimal concentrations will vary based on individual development conditions.
Sodium is highly reactive with water. This suggests that it may be useful for enhanced oil recovery. However, this also complicates its preparation – too early exposure to water will lead to failure. The researchers solved this problem by preparing sodium nanoparticles in silicone oil, allowing the substance to disperse throughout the reservoir before it comes into contact with the water in the reservoir, causing smaller chemical reactions over a larger area. It is also possible to disperse sodium nanoparticles in other solvents, including pentane and kerosene, or even mix them with polymers or surfactants to achieve higher oil recovery.
While the paper focuses on the use of nanofluids to enhance heavy oil recovery, scientists note that it can also be used in light oil production and for more general domestic purposes such as cleaning pipes clogged with grease.