The objective of the present study is to investigate wellbore cement alteration due to CO${}_2$-rich brine interaction under reservoir conditions. Hence, an experiment made with a unique large-scale autoclave system has been numerically simulated. Results from that experiment showed an alteration zone of 3 mm thickness at the bottom of the cemented casing, where the cement interacted with the CO${}_2$-rich brine. A reactive transport model has been made in order to understand the geochemical processes that occurred during the experiment and the impact of mineral changes on the cement porosity. The numerical model allowed to determine the diffusion coefficient of the cement by calibration using the alteration thickness. Results revealed an increase of porosity at the inner rim due to C-S-H and portlandite dissolution, followed by a drop of porosity due to mainly calcite, but also, C-A-S-H and M-S-H precipitation, and finally, an increase of porosity in the last mm due to portlandite dissolution. In the rest of the 2 m cement column, neither mineral nor porosity changes are predicted by the numerical model, indicating that the well integrity practically would not be affected for the period of time of exposure to dissolved CO${}_2$.

本研究的目的是调查 CO 引起的井筒水泥蚀变${}_2$- 储层条件下丰富的盐水相互作用。因此，已经对使用独特的大型高压釜系统进行的实验进行了数值模拟。该实验的结果表明，在固井套管底部有一个 3 毫米厚的蚀变带，在那里水泥与二氧化碳相互作用${}_2$- 丰富的盐水。为了了解实验过程中发生的地球化学过程以及矿物变化对水泥孔隙度的影响，建立了反应输运模型。数值模型允许通过使用蚀变厚度进行校准来确定水泥的扩散系数。结果表明，由于 CSH 和硅酸盐溶解，内缘孔隙度增加，随后主要是方解石，CASH 和 MSH 沉淀导致孔隙度下降，最后，由于硅酸盐，最后 mm 孔隙度增加解散。在 2 m 水泥柱的其余部分，数值模型没有预测矿物和孔隙度的变化，表明在暴露于溶解的 CO 的时间段内，井的完整性实际上不会受到影响${}_2$.