United States. Materials scientists at the Southwest Research Institute (SwRI) have developed a superhydrophobic coating and a process to apply it to the inner surfaces of long tubular structures. The technology is primarily designed to mitigate or prevent hydrates and other deposits from adhering to underwater pipes.
Hydrates are ice-like solids composed of water and a gas, typically methane or carbon dioxide. Hydrates have a density close to that of ice and can look like muddy ice. However, the gas molecules contained in hydrates stabilize crystals and allow hydrates, unlike ice, to form at temperatures as high as 70°F in hydrocarbon systems, such as production flow lines. Hydrates can be deposited on the inner wall of the pipe and accumulate until they completely block the flow line and stop the transport of hydrocarbons to the processing facility.
Currently, hydrate formation is prevented using chemical additives or physical methods, such as heating jackets or high-frequency electromagnetic fields, either of which adds engineering complexity and expense. Also, when these methods fail, removing hydrate plugs can be expensive.
In deep oil wells, the paraffin and asphaltene components in the oil can also be deposited on the inner wall of the pipe and impede the flow of product from the well, requiring costly prevention and remediation measures.
"We have developed a family of coatings and a process technology called Lotus, a reference to the lotus flower, which has similar superhydrophobic properties," said Institute scientist Dr. Michael Miller. "We produce these coatings using a vacuum process in which a plasma is ignited, a state of matter consisting of free electrons plus ionized atoms and molecules, within the entire length of the pipe, while one or more chemicals are introduced. The process selectively fragments the chemicals into ions that are then accelerated on the surface of the pipe where they immediately undergo polymerization to form a thin, glass-like, durable coating," he added.
SwRI's Lotus family of coatings is unique in that their surface properties, such as surface energy or tension, can be chemically adapted to prevent different types of deposits from adhering to the inside of the pipe.
Under an exclusive licensing and technology transfer agreement, Lotus' coating technology is being transferred to an energy services company for the large-scale production of coated pipes so that the sponsoring customer can further demonstrate its performance in offshore well applications.
"The construction of a high-performance coating facility specifically for Lotus coating technology is underway. Over time, it will provide enough production capacity to meet the needs of other customers in the oil and gas industry," Miller added.
Source: Southwest Research Institute.
