Evolution of voids and fractures in wellbore cement under dynamic flow conditions relevant to geological carbon sequestration

P. Cao, Zuleima Karpyn, L. Li

Research output: Contribution to journalArticlepeer-review

Abstract

Interaction between wellbore cement and injected CO2 is one of the main processes that can potentially alter cement properties. Cracks/fractures inside cement plugs or weak bonding between formation/cement, may form preferential leakage pathways due to cement alteration during geological carbon sequestration. This work investigates the evolution of cement properties under dynamic flow conditions. A cement casted sandstone core of 3.81 cm diameter and 7.67 cm long, with voids and fractures in the central cemented region was made. The cemented sandstone core was flooded continuously using CO2-saturated brine under pressure and temperature conditions relevant to carbon sequestration. Changes in cement and void space were visualized and quantified using X-ray Micro-CT imaging. Within an eight-day flow-through period, the cement zone experienced chemical alterations evident through color changes as well as changes in fracture volume, surface area, and structure while the host sandstone remained unaltered. A higher rate of cement degradation was observed in the early stage of CO2-saturated brine flooding. The rate of cement alteration varies spatially due to brine acidity variation along the core, such that fracture apertures located near the core inlet experienced more severe cement degradation than those closer to the core outlet, by a factor of two.

Original languageEnglish (US)
JournalAnnual AAPG Convention (Pittsburgh, PA, 5/19-22/2013) Abstracts
StatePublished - Oct 3 2013

All Science Journal Classification (ASJC) codes

  • Energy(all)

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