基于HYMOSTRUC3D的固井水泥石孔隙结构演变及力学强度发展规律

固井水泥石微结构发育规律是固井工艺设计和固井质量评价的重要参考依据.以HYMOSTRUC3D软件为基础,建立了水泥水化模型,获取了CHCH表示Ca(OH)2晶体]含量和抗压强度,并对实验结果进行了对比,模拟结果与实验结果的偏差基本都在10％以内.然后,基于水泥水化模型获取了不同水灰比(W/C,W/C=0.4、0.44、0.5、0.6、0.8、1.0、2.0)和水化龄期对固井水泥浆水化过程中C3S(3CaO·SiO2),C2S(2CaO·SiO2),C3A(3CaO·Al2O2),C4AF(4CaO·Al2O3·Fe2O3),C-S-H(Ca5Si6O16(OH)·4H2O)CH、孔隙率、孔径分布、抗压强度和三维结构等的影响.同时,采用Ryshkewitch方程、Schiller方程和二次线性方程重点讨论了抗压强度与孔隙率的关系.结果表明:在水泥水化过程中,随水化反应的进行,水泥石孔隙率逐渐减小,抗压强度增大;随水灰比增大,粗孔含量增加,细孔占比减小,孔隙率增大,孔径分布变宽,抗压强度减小.采用Ryshkewitch方程、Schiller方程和二次线性方程拟合抗压强度与总孔隙率和毛细孔隙率的相关系数都达到0.92以上,分别为0.96、0.92、0.95和0.98、0.97、0.98;毛细孔隙率是固井水泥石强度发展的主要影响因素.

Research on pore structure evolution and strength development of set cement based on hymostruc3d

The microstructure development of cement stone is an important reference for cementing process design and cementing quality evaluation.Based on the software hymostruc3d, the hydration model of cement was established, and the ch content and compressive strength were obtained. The experimental results were compared. The deviation between the simulation results and the experimental results was basically within 10%.Then, based on the cement hydration model, the effects of different water cement ratiosW/C (W/C = 0.4, 0.44, 0.5, 0.6, 0.8, 1.0, 2.0) and hydration age on C3S, C2S, C3a, c4af, C-S-H, CH, porosity, pore size distribution, compressive strength and three-dimensional structure of cement slurry were obtained based on cement hydration model.At the same time, ryshkewitch equation, Schiller equation and quadratic linear equation are used to discuss the relationship between compressive strength and porosity.The results show that: in the process of cement hydration, with the hydration reaction, the porosity of cement paste decreases gradually, and the compressive strength increases; with the increase of water cement ratio, the content of coarse pores increases, the proportion of fine pores decreases, the porosity increases, the pore size distribution widens, and the compressive strength decreases.Using ryshkewitch equation, Schiller equation and quadratic linear equation, the correlation coefficients between compressive strength and total porosity and capillary porosity are all above 0.92, which are 0.96, 0.92, 0.95 and 0.98, 0.97 and 0.98 respectively. Capillary porosity is the main influencing factor of cement strength developmen.