Imaging Wellbore Cement Degradation by Carbon Dioxide under Geologic Sequestration Conditions Using X-ray Computed Microtomography
ABSTRACT: X-ray microtomography (XMT), a nondestructive three-dimensional imaging technique, was applied to demonstrate its capability to visualize the mineralogical alteration and microstructure changes in hydrated Portland cement exposed to carbon dioxide under geologic sequestration conditions. Steel coupons and basalt fragments were added to the cement paste in order to simulate cement-steel and cement-rock interfaces. XMT image analysis showed the changes of material density and porosity in the degradation front (density: 1.98 g/cm3, porosity: 40%) and the carbonated zone (density: 2.27 g/cm3, porosity: 23%) after reaction with CO2- saturated water for 5 months compared to unaltered cement (density: 2.15 g/cm3, porosity: 30%). Three-dimensional XMT imaging was capable of displaying spatially heterogeneous alteration in cement pores, calcium carbonate precipitation in cement cracks, and preferential cement alteration along the cement-steel and cement-rock interfaces. This result also indicates that the interface between cement and host rock or steel casing is likely more vulnerable to a CO2 attack than the cement matrix in a wellbore environment. It is shown here that XMT imaging can potentially provide a new insight into the physical and chemical degradation of wellbore cement by CO2 leakage.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1062502
- Report Number(s):
- PNNL-SA-93100; AA9010200
- Journal Information:
- Environmental Science and Technology, Vol. 47, Issue 1; ISSN 0013-936X
- Publisher:
- American Chemical Society (ACS)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Wellbore cement fracture evolution at the cement–basalt caprock interface during geologic carbon sequestration
Effective Permeability Change in Wellbore Cement with Carbon Dioxide Reaction