NaCl gradient controls Ca leaching of C-S-H in oil well cement at 260℃: From strength enhancement to degradation
Year: 2025
Type: article
Abstract: With development of deep offshore and salt-layer resources, the advancement of high-temperature salt-resistant cement becomes a globally urgent priority for cementing technology reserves. However, the coupled effects of NaCl and high temperature on the microstructure of cement pastes remain unclear. This paper investigated the microstructure change of cement pastes with different concentrations of NaCl cured at 260°C and 21 MPa using multi-scale characterization. The results showed that NaCl led to the decalcification of C-S-H, while Na + and Al 3+ enhanced the polymerization degree of C-S-H through charge compensation. This process increased the packing density of C-S-H and promoted the formation of reyerite, thereby improving compressive strength of cement pastes. However, higher NaCl concentration led to leaching of interchain calcium, causing structural degradation of xonotlite. The reduced free energy of Ca dissolution enhanced the thermodynamic spontaneity of transformation from xonotlite to wollastonite. This transformation caused the strength retrogression of cement pastes at high temperature.
Authors: Chenzi Geng, Jiafeng Wang, Xiao Yao, Chunyu Wang, Shaowei Zheng, Duyou Lu, Zuhua Zhang
Institutions: Nanjing Tech University, Tongji University
Language: English
Subfield: Civil and Structural Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,660
Funders: Jiangsu Provincial Department of Education, Nanjing Tech University, Priority Academic Program Development of Jiangsu Higher Education Institutions, Graduate Research and Innovation Projects of Jiangsu Province, Jiangsu Collaborative Innovation Center for Advanced Inorganic Functional Composites
Award: G355754285
OpenAlex ID: W7083021664