In a novel program, scientists at Kazan Federal University (KFU) (Kazan, Russia) are planning to apply sunflower oil-based inhibitors in harsh Arctic conditions, with a goal of preventing gas hydrates and corrosion during oil and gas production.
According to the university, these unique bio-based reagents have shown high efficiency during recent laboratory tests, and they believe this can prevent freezing in wells that are producing hydrocarbon resources in the Arctic.
Limitations of Traditional Methods
With regards to “gas hydrate plugs,” the researchers say there are several generally accepted strategies to deal with the problem. Historically, the most common and simplest method is to cut them out. But this method is often ineffective, unsafe, and outdated, according to the researchers, who note that the technology has largely been replaced by inhibitors.
However, they caution that most of the currently existing inhibitors have different concerns, such as being environmentally unsafe or overly expensive. Therefore, the researchers began searching for a budget-friendly and biodegradable product with unique properties.
"We found that sunflower oil can be modified in several ways, and many molecules can be synthesized from it,” says Abdolreza Farhadian, research associate. “The presence of alkyl chains in its structure can improve hydrate inhibition. Sunflower oil-based molecules can easily degrade due to the presence of ester groups in their structure.”
Unique Environmental Concerns
In offshore fields, the researchers say it is impossible to ignore environmental issues, and components should not be toxic. Therefore, the task of scientists on this project was not only to ensure the effectiveness of an inhibitor, but also to ensure environmental safety for the aquatic environment and its inhabitants.
“When we were developing this reagent, we were looking for a basis for the synthesis of molecules that would be the least toxic, biodegradable, and paid attention to natural compounds, primarily natural oils,” says Mikhail Varfolomeev, head of hydrocarbon research at KFU.
“From the point of view of chemistry, it was sunflower oil that interested us,” Varfolomeev says. “First, it allows, by its structure, to implement exactly the synthesis method that we have invented. Secondly, sunflower oil is just a natural product, non-toxic and biodegradable. Exactly what we need.”
Hydrate Inhibition Experiments
In a press release,1 the researchers contend that their “fairly affordable and inexpensive tool” can be a solution to large-scale problems. They add that the technique can be “easily implemented in modern industry.” In experimental work, Kazan researchers partnered with colleagues from the Russian Oil and Gas University (Moscow, Russia), Shahid Beheshti University (Tehran, Iran) and the University of Isfahan (Isfahan, Iran).
During a series of hydrate inhibition experiments, results revealed that phosphorylated waterborne polyurea/urethane (Ph-WPUU) can significantly reduce the average onset temperature and delay the induction time of hydrate nucleation, when compared to pure water. The Ph-WPUU product was found to significantly decrease gas hydrate nucleation and growth rates, with maximum corrosion inhibition efficiency reached 96% at 700 ppm concentration.
Moreover, the quantum chemical study revealed that the presence of the triglyceride group of sunflower oil in the Ph-WPUU structure played an effective role as an active site to interact with the carbon steel surface. These results indicate that the application of Ph-WPUU provides a bio-based strategy to develop and design single polymer molecules, which exhibit both hydrate and corrosion inhibition.
"It should be noted that the new sunflower oil-based inhibitor also allows the simultaneous killing of two birds with one stone—gas hydrates and pipeline corrosion. In the presence of such complications in oil and gas production, the proposed multifunctional inhibitors can be more effective than reagent mixtures used in industry,” concludes Andrey Stopore, a senior research associate at KFU and co-author of a paper on the topic.
The KFU team notes that this development is not the group’s first “green” technology invention. In 2019, these researchers synthesized castor oil-based inhibitors. Further information on their latest work is available in a November 2020 paper published in the international energy engineering research journal, Energy.
Source: Kazan Federal University, kpfu.ru/eng.
1 “Sunflower Oil Shows Unexpected Efficiency in Corrosion Prevention,” Kazan University News, Aug. 28, 2020, https://kpfu.ru/eng/news-eng/sunflower-oil-shows-unexpected-efficiency.html (Sept. 16, 2020).