Barbara Kutchko

Foamed Cement Analysis With Computed Tomography

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.Copyright

Wellbore Cement Integrity under Geologic Carbon Storage Conditions

Carbon capture and geologic storage is a strategy to reduce CO 2 emissions from large point sources and mitigate climate change. The key to successful CO 2 storage is to assure a very high degree of retention of the injected CO 2 within the target CO 2 -storage aquifer, so that little to no potential remains for injected CO 2 to return to the atmosphere. The majority of locations that are being considered for CO 2 injection are in areas that have a history of oil and natural gas production. As a result, candidate formations for CO 2 storage are typically penetrated by a significant number of wells from previous oil/gas exploration and production. The potential exists for CO 2 to escape the CO 2 -storage formation through existing or abandoned wells. Investigation of the ability of wellbore cement in existing and abandoned wells to resist alteration due to cement–CO 2 interaction is necessary.

IMAGE ANALYSIS OF GAS WELL CEMENT EXPOSED TO COAL MINE WATER

References This study demonstrates the viability of using image processing software, in this study, ImageJ, to measure porosity of cement cores. In this work, cement porosity increases exposure to coal mine water increases. Not only does porosity increase overall, but image processing analysis suggests that rim porosity increases more than interior porosity specifically due to the development of dissolution veins along the rim. The range of relative standard deviation for rim measurements suggest that the heterogeneous nature of the cement may result in localized reactions that affect porosity. Image processing software provides a method to visualize and quantify the cement alteration process. Map of Pennsylvania that features