Calcium carbonate precipitation and its effects on the degradation of oil well cement
Decalcification of cement in solutions of carbonated brine is important to a host of engineering applications, especially in subsurface service environments where cementitious materials are frequently utilised as engineered barriers for wellbore seals, as well as shaft and drift seals and waste forms for nuclear waste disposal.
Significant impact on cement reactivity
Analysis of leaching simulations and experiments shows that, depending on solution compositions (dissolved CO2 concentration, pH, Ca ion concentration), calcite precipitation occurring during leaching of cement in contact with carbonated brine can have a significant impact on cement reactivity, in some instances leading to complete arrest of reactivity via calcium carbonate “pore-clogging”.
Analysis of pore-clogging
Scientists recently presented modeling and experimental results that examine the range of solution conditions that can lead to pore-clogging. Analysis of the results shows that distinct regimes of leaching behavior, based on pH and pCO2, can be used to form a framework to better understand the occurrence of pore-clogging.
The study is published in: Cement and Concrete Research Volume 113, November 2018, Pages 1-12.
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