Cement degradation under conditions relevant to geological carbon sequestration

Li Li, Leopold Brunet, Zuleima Karpyn, Brian Strazisar, Barbara Kutchko

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Assessing the potential risks of CO2 leakage from deep subsurface is one of the major challenges for geological carbon sequestration. Injected CO2 can dissolve into in situ brine to produce acidity for cement wellbore degradation. This degradation can potentially change the properties of the cement and decrease its structural integrity. Wellbore integrity assessment is essential for predicting the risk of leakage because degraded cement can open pathways for CO2 leakage. In this work, we develop a reactive transport model based on experimental observations to obtain quantitative and mechanistic understanding of the coupled reactions and diffusion processes involved in cement degradation. This work also aims to quantify the effect of initial cement properties, in particular porosity and the abundance of portlandite, on the rate and extent of cement degradation. The results show that the leaching of calcium ions during the acid attack of the cement leads to precipitation of calcite near the cement brine interface. This precipitation yields a localized reduction in porosity, which reduces the diffusion process and the penetration of the degradation inside the cement sample. The calcite precipitation is largely affected by the initial porosity and portlandite content. Increasing content of portlandite allows a thicker calcite precipitation thus decreasing the extent of degradation. Increasing initial porosity leads to faster diffusion of the acidic brine and less porosity reduction by the calcite precipitation. As a result, it increases the rate and extent of cement degradation. The ratio of the initial portlandite content and the porosity is a critical indicator of the severity of cement degradation. The results allow us to better understand cement behavior when exposed to CO 2-saturated brine under geological sequestration conditions and to predict the rate and extent of cement degradation with given cement properties.

Original languageEnglish (US)
Title of host publicationAIChE 2012 - 2012 AIChE Annual Meeting, Conference Proceedings
StatePublished - 2012
Event2012 AIChE Annual Meeting, AIChE 2012 - Pittsburgh, PA, United States
Duration: Oct 28 2012Nov 2 2012

Other

Other2012 AIChE Annual Meeting, AIChE 2012
CountryUnited States
CityPittsburgh, PA
Period10/28/1211/2/12

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All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Chemistry(all)

Cite this

Li, L., Brunet, L., Karpyn, Z., Strazisar, B., & Kutchko, B. (2012). Cement degradation under conditions relevant to geological carbon sequestration. In AIChE 2012 - 2012 AIChE Annual Meeting, Conference Proceedings