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Viscosity Equations
Researchers Working to Connect the Dots Between Bubbles and Viscosity in Foamed Cement

A team of researchers from NETL and Carnegie Mellon University (CMU) recently developed equations to more simply determine how the viscosity of foamed cement is affected by the addition of bubbles into the slurry. Understanding the connection between an increase of bubbles concentration and the ensuing changes in viscosity is crucial for predicting how well the foamed cement will perform in wellbores, which will enable safer oil and gas production. The work was recently featured in a special issue of  Fluids, an international journal.

“Optimizing foamed cement properties is important for many oil and gas operations,” said NETL researcher Eilis Rosenbaum, Ph.D., who co-authored the paper along with fellow NETL researcher Mehrdad Massoudi, Ph.D., and Kaushik Dayal, Ph.D., from CMU. “It creates a barrier between the pipe and the surrounding rock that prevents migration of fluids between formations or to the surface.”

Foamed cement, rather than traditional cement, is used because the added bubbles reduce density while imparting improved mechanical properties that come with increased viscosity. Oil and gas producers add nitrogen into the cement slurry to create the bubbles in an attempt to achieve around 35% gas volume, which the American Petroleum Institute (API) recommends for an optimal foamed cement.

In this study, the research team leveraged powerful computational resources to simulate the arrangement of different percentages of bubbles within a defined amount of cement. Based on those simulation results, the researchers then developed a set of equations that defined the change in viscosity due to the addition of bubbles.

“When we compared the computed results to known experimental data, we saw that the results matched,” Rosenbaum said. “Now, rather than conducting experiments, which can influence or change the properties being measured, or running more simulations, which requires significant computational resources, we can use these equations to predict the effects of the addition of bubbles to the cement.”

This work builds from knowledge gained in two previously published papers by Rosenbaum, Massoudi and Dayal, which detailed the interactions taking place in foamed cement that enabled the simulations and equation development.

Industry, academia and government all rely on NETL’s globally recognized foamed cement research for accurate and dependable information on oil and gas wellbore performance, and with this new simpler approach to predicting foamed cement viscosity, the Lab is helping to save valuable time and resources.