Evaluation of SC-CO2–brine on the micro-mechanical properties of lamina shales by micro-scratch test

• DOI: 10.1016/j.petsci.2024.07.017
• Publication Date: 2024-07-18T08:35:00Z
• Authors: Liu Yang; Zhao-Yang Liu; Yuan-Xun Nie; Zhen-Chuan Han; Fei Gong; Ming-Jun Li; Yan Liu

The mechanism of SC-CO2–brine–rock interaction (SCBRI) and its effect on the mechanical properties shale are crucial for oil development CO2 sequestration. To clarify influence SCBRI micromechanics shale, lamina matrix were saturated with SC-CO2–brine 2, 4, 6, 8 days, respectively. micro-scratch technique was then used to measure localized fracture toughness before after saturation. Combining results SEM-QEMSCAN-EDS analysis, differences in mineral composition (primarily composed carbonate minerals) clay studied. QEMSCAN analysis indicate distinct mineralogical compositions between matrix. showed that: (1) leads decrease content significant increase porosity laminar cracks. In addition, damage degree increased at saturation 6 days. (2) weakens shale. scratch depth by 34.38% 1.02%, decreased 13.11%. It a trend first increasing decreasing. (3) enhances plastic deformation behavior index increases 18.75% 21.58%, These great significance evaluating gas extraction CO2.