Structural evolution in micro-calcite bearing Ca-montmorillonite reinforced oilwell cement during CO2 invasion. (10th January 2022)

• Record Type: Journal Article
• Authors: Mei, Kaiyuan; Zhang, Liwei; Wang, Yan; Cheng, Xiaowei; Xue, Quan; Gan, Manguang; Fu, Xiaojuan; Zhang, Chunmei; Li, Xiaochun
• Is Part Of: Construction & building materials. Volume 315(2022)
• Publication Date: 2022-01-10
• Subjects: Supercritical CO2 -- Oilwell cement -- Structural evolution -- Microcrystal modification; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.125744
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Ca-montmorillonite, modified by ScCO2, is used as an anti-CO2 corrosion additive. Micro-calcite (MC) bearing Ca-montmorillonite reduces degradation of oilwell cement. MC induces formation of a dense carbonate layer, which enhances CO2 resistance. Abstract: High concentration CO2 invades and forms carbonate layers in oilwell cement under geological CO2 sequestration conditions. Long-term invasion of CO2 makes the carbonation structure unstable and prone to damage. For the reinforcement of oilwell cement, Ca-montmorillonite (Ca-MMT) was modified using supercritical CO2 (ScCO2 ) as the solvent and intercalator. The micro-calcite bearing Ca-montmorillonite (MC Ca-MMT) was added to the cement slurry to reinforce the oilwell cement after the modification. Microcrystal calcite was identified in the MC Ca-MMT through transmission electron microscopy(TEM) and selected-area electron diffraction(SAED) analyses. The mechanical properties and microstructural evolution of the MC Ca-MMT reinforced oilwell cement were investigated, revealing that the carbonation was inhibited by MC Ca-MMT. Through the analysis of microcrystal formation and densified carbonation area, the CO2 -resisting mechanisms of MC Ca-MMT reinforced oilwell cement were revealed in this study.