Dr. Liwei ZhangProfessor, Institute of Rock and Soil Mechanics (IRSM), Chinese Academy of Sciences, China
Speech Title: Synthesis and Application of Micro-calcite Bearing Ca-montmorillonite Reinforced Oilwell Cement in CO2-rich Environments
Abstract: High concentration CO2 invades oilwell cement under geological CO2 storage or sour oil and gas exploitation conditions. Long-term invasion of CO2 makes oilwell cement 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.
Keywords: Supercritical CO2, Oilwell cement, Montmorillonite, Microcrystal calcite, Structural evolution.
Biography: Liwei Zhang is a professor at Institute of Rock and Soil Mechanics (IRSM), Chinese Academy of Sciences. He got his B.E. degree from Harbin Institute of Technology in 2008, M.S. degree from Duke University in 2010, and Ph.D. degree from Carnegie Mellon University in 2013. Prof. Zhang's research has been focused on cement additives and mineral dissolution/precipitation processes. Specific research areas include development of corrosion-resisting cement additives, carbonation of cement and concrete, subsurface mineral dissolution and precipitation under geologic carbon storage conditions, etc.. His research activities have resulted in 1 book, 5 book chapters, 17 patents and more than 100 journal articles and conference proceedings. Prof. Zhang is a committee member of the Energy and Environment Division of China Energy Society, and a committee member of the Climate Change Division of Chinese Society for Environmental Sciences.