skip to main content


Title: Assessment of two-phase flow on the chemical alteration and sealing of leakage pathways in cemented wellbores

Wellbore leakage tops the list of perceived risks to the long-term geologic storage of CO 2, because wells provide a direct path between the CO 2 storage reservoir and the atmosphere. In this paper, we have coupled a two-phase flow model with our original framework that combined models for reactive transport of carbonated brine, geochemistry of reacting cement, and geomechanics to predict the permeability evolution of cement fractures. Additionally, this makes the framework suitable for field conditions in geological storage sites, permitting simulation of contact between cement and mixtures of brine and supercritical CO 2. Due to lack of conclusive experimental data, we tried both linear and Corey relative permeability models to simulate flow of the two phases in cement fractures. The model also includes two options to account for the inconsistent experimental observations regarding cement reactivity with two-phase CO 2-brine mixtures. One option assumes that the reactive surface area is independent of the brine saturation and the second option assumes that the reactive surface area is proportional to the brine saturation. We have applied the model to predict the extent of cement alteration, the conditions under which fractures seal, the time it takes to seal a fracture, and themore » leakage rates of CO 2 and brine when damage zones in the wellbore are exposed to two-phase CO 2-brine mixtures. Initial brine residence time and the initial fracture aperture are critical parameters that affect the fracture sealing behavior. We also evaluated the importance of the model assumptions regarding relative permeability and cement reactivity. These results illustrate the need to understand how mixtures of carbon dioxide and brine flow through fractures and react with cement to make reasonable predictions regarding well integrity. For example, a reduction in the cement reactivity with two-phase CO 2-brine mixture can not only significantly increase the sealing time for fractures but may also prevent fracture sealing.« less
 [1] ;  [2] ;  [1] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Univ. of New South Wales, Sydney, NSW (Australia)
Publication Date:
Report Number(s):
Journal ID: ISSN 1750-5836
Grant/Contract Number:
Accepted Manuscript
Journal Name:
International Journal of Greenhouse Gas Control
Additional Journal Information:
Journal Volume: 69; Journal Issue: C; Journal ID: ISSN 1750-5836
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; carbon storage; two-phase flow; wellbore integrity; cement-CO2 reactions
OSTI Identifier: