Research on the influence of polyanionic cellulose on the microstructure and properties of oil well cement

Drilling fluid additive is an important factor of contamination between cement paste and drilling fluid, in which PAC is the most significant one. This work investigated the effects of PAC on the hydration process and properties of cement by using X-ray diffraction (XRD), Different scanning thermal analyzer (DSC), Fourier transform infrared spectrometer (FTIR) and Zeta-potential. Based on the results of Environment Scanning Electron Microscopy (ESEM), the evolution of the microstructure of polymer-cement could be well explained by Ohama model. Combining with the rheological and mechanical measurements, it's surmised that H2O could bind with -OH of PAC through hydrogen bond to form cross-linking structure and trapping free water, which lead to the deterioration of rheological properties and inhibit the hydration process, accompanied by reduction of C-S-H content to decrease the compressive strength. Fe3+ and Al3+ released by cement hydration induced PAC to form gel through the formation of dynamic ion bonds and hinder the homogeneous dispersion of cement particles, proving that the deterioration of rheology properties is result of coupling effects of hydrogen and ion bond. According to the mechanism, using Al3+ and Fe3+ metal masking agent or raising pH could mitigate the contact contamination and increase the safety of cementing. (C) 2020 Elsevier Ltd. All rights reserved.