Inorganically crosslinked polymers have been intensively implemented for conformance control treatments in oil and gas wells at low temperatures (<90°C) because of their faster gelation time compared to organically crosslinked gels. Crosslinkers such as chromium acetate are known to be toxic, and aluminium-based alternatives have been introduced. This study aims to investigate the impact of aluminium acetate (AlAc) particle size on the gelation kinetics of polyacrylamide (PAM)-based gels at a pH of 5 and temperature of 75°C. Moreover, bentonite is used as an additive to delay the crosslinking of PAM/AlAc gels. Reducing the particle size increases the specific surface area of the particles and provides more crosslinking sites. Therefore, lower PAM concentrations (up to 5 wt.%) could be used without AlAc settling. Using 7 wt.% PAM/1 wt.% AlAc with sizes of 25 and 48 μm revealed a crosslinking time of 17 and 115 min, respectively. The addition of bentonite at low crosslinker concentrations (0.5–1 wt.%) did not decrease the gel strength of 7 wt.% PAM/1 wt.% AlAc significantly. The gelation time was extended after adding 1 wt.% bentonite to the formulation where the delay was attributed to the adsorption of AlAc on the bentonite surface that was illustrated by molecular simulation.

中文翻译：

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醋酸铝粒径对聚丙烯酰胺凝胶凝胶动力学的影响：流变学和分子模拟研究

由于与有机交联凝胶相比，无机交联聚合物具有更快的凝胶时间，因此无机交联聚合物已被广泛用于低温（<90°C）油气井的一致性控制处理。众所周知，醋酸铬等交联剂有毒，因此引入了铝基替代品。本研究旨在研究醋酸铝 (AlAc) 粒径对基于聚丙烯酰胺 (PAM) 的凝胶在 pH 值为 5 和温度为 75°C 下的凝胶动力学的影响。此外，膨润土用作延迟 PAM/AlAc 凝胶交联的添加剂。减小粒径会增加颗粒的比表面积并提供更多的交联位点。因此，可以使用较低的 PAM 浓度（高达 5 wt.%）而不用 AlAc 沉降。使用 7 wt.% PAM/1 wt. 尺寸为 25 和 48 μm 的 % AlAc 显示交联时间分别为 17 和 115 分钟。在低交联剂浓度（0.5-1 wt.%）下添加膨润土不会显着降低 7 wt.% PAM/1 wt.% AlAc 的凝胶强度。在将 1 wt.% 膨润土添加到配方中后胶凝时间延长，其中延迟归因于 AlAc 在膨润土表面上的吸附，这由分子模拟说明。