Cement properties characterization from a section retrieved from an oil production well after 33 years of downhole exposure

• Published in: Journal of petroleum science & engineering 2022-01, Vol.208, p.109334, Article 109334
• Main Authors: Beltrán-Jiménez, Katherine, Gardner, Dave, Kragset, Steinar, Gebremariam, Kidane F., Reales, Oscar A.M., Minde, Mona W., de Souza, Marcelo I.L., Aasen, Jan A., Skadsem, Hans J., Delabroy, Laurent
• Format: Article
• Language: English
• Subjects: Cement characterization; Cement durability; Plug & abandonment; Well integrity
• ISSN: 0920-4105; 1873-4715
• DOI: 10.1016/j.petrol.2021.109334

A unique data set has been constructed based on the study of class G cement recovered from an oil well on the Norwegian continental shelf. The cement was placed between two casing sections and submitted to downhole conditions for 33 years. The aim of this research is to analyze the aging of the cement and its consequences for the well integrity. Additionally, the findings represent a baseline for future assessments of old age cement from oil and gas wells. The characterization includes: petrophysical properties (porosity and permeability); mechanical properties (uniaxial compressive strength (UCS) and Young’s Modulus); and compositional analysis using Computed Tomography (CT), Scanning Electron Microscopy (SEM), X-ray Fluorescence (XRF) and Quantitative X-ray Diffraction (XRD). Findings suggest that the overall decrease of cement integrity appears to be low, since the magnitudes of permeability and porosity fall within the ranges of early age cement. However, the chemical characterization shows that mud contamination may have an effect on the cement performance and is found to be relevant for a reduction in compressive strength. •In-depth characterization of class G cement exposed to downhole conditions for 33 years.•The results presented provide a baseline to assess the effect of aging on cement.•Findings suggest that the decrease in cement integrity appears to be low.