Solid crude oil: Researchers explore how to get clogged wells moving
Crude oil extracted from the earth often contains many substances that are hydrocarbon-based, such as other liquids, dissolved solids and gases. Of these, asphaltene, a dissolved solid and key ingredient in asphalt, can be problematic. When underground pressure changes occur in reservoirs during oil extraction, asphaltenes can re-solidify and block a well in a process called precipitation.
Berna Hascakir, Flotek Industries Inc. Career Development Professor in the Harold Vance Department of Petroleum Engineering, addressed precipitation in two research projects that investigated the reservoir ratios and polarity properties of asphaltenes. She found a way to predict the conditions under which asphaltenes become solid and used methods based on dielectric properties to get the solid material moving again.
Asphaltene, like many substances in the earth, changes phase as pressures or temperatures vary. The problem lies in predicting which conditions bring about the change.
“Think about water,” said Hascakir. “When you lower the temperature of water at atmospheric pressure you make ice, which is solid. In the same way, you have a liquid crude oil and you’re lowering the pressure during oil production. This change makes the crude oil solid, like ice.”
The effects of pressure and temperature on asphaltenes have been well researched, but the variations in oil chemistry and the dielectric constants of reservoir materials that can affect this phase change have not. Hascakir and her students studied these facets of the problem and found the ratios of asphaltenes and other components to oil within the reservoir fluids was significant. The dielectric properties that determine whether reservoir materials were polar or non-polar also affected outcomes. Hascakir devised a method that uses this information to reliably predict conditions where precipitation was likely to happen. Her method will help oil companies address the problem before solidification occurs and plugs up their expensive wells.
“We were issued a patent on that method,” said Hascakir. “A chemical company currently owns the rights of the patent. They say our method is one of the best to determine the asphaltenes’ stability, and they hired my former student, Abhishek Punase, who was working on that project.”