Foamed Cement Analysis With Computed Tomography

Abstract

Foamed cements are widely used for cementing oil or gas wells that require lightweight slurries, gas migration prevention, or wells in high-stress environments. When this manufactured slurry solidifies in the sub-surface environment the distribution of gas voids can affect the resultant strength, permeability, and stability of the wellbore casing. Researchers at the National Energy Technology Laboratory have produced the first high-resolution X-ray computed tomography (CT) three-dimensional images of atmospheric and field generated foamed cement across a range of foam qualities. CT imaging enabled the assessment and quantification of the foamed cement structure, quality, and bubble size distribution in order to provide a better understanding of this cement. Ultimately, this research will provide industry the knowledge to ensure long-term well integrity and safe operation of wells in which foamed cements are used. Initial results show that a systematic technique for isolating air voids can give consistent results from the image data, laboratory generated foamed cements tend to be uniform, and that high-gas fraction foamed cements have large interconnected void spaces.