Aluminum citrate is used as a conformance control agent to improve oil production and excess water production. This paper discusses the formation of mono and polynuclear aluminum species from the synthesis of aluminum citrate and evaluates these compounds as crosslinkers in hydrogels for conformance control. The products obtained from the synthesis were characterized by Fourier-transform infrared spectrometry (FTIR), elemental analysis (CHN), scanning electron microscopy (SEM), and inductively coupled plasma–optical emission spectrometry (ICP-OES). The FTIR analyses indicated the presence of mononuclear aluminum citrate complexes at pH 3 and polynuclear species starting at pH 4. These results were corroborated by CHN and ICP-OES techniques, which revealed the variation of carbon, oxygen, hydrogen, and alumina precipitate levels as functions of pH variation. The focus of the study was to assess how these crosslinking agents perform in hydrogel formation under reservoir conditions. Rheological analysis showed that the values of tan (delta) of the hydrogel synthesized with aluminum citrate at pH 6 were lower than 0.1, indicating strong gels, while at pH 9, the values were above 0.1, indicating weak gels. These results are in agreement with those obtained by FTIR, which showed that at pH 6, the structures of the aluminum citrate complex were probably in the form [Al₃(C₆H₅O₇)₃(OH)₄(H₂O)]⁴⁻. This structure appears to allow easier access to the aluminum orbital for the crosslinking process compared to the gel composed of aluminum citrate synthesized at pH 9 [Al₃(C₆H₆O₇)₃(OH)₄(H₂O)₅]⁴⁻.

中文翻译：

---

柠檬酸铝化合物的合成，表征及其对聚丙烯酰胺基水凝胶形成影响的评价

柠檬酸铝被用作一致性控制剂，以改善产油量和过量产水量。本文讨论了柠檬酸铝合成过程中单核和多核铝物种的形成，并评估了这些化合物作为水凝胶中的交联剂以进行一致性控制。从合成中获得的产物通过傅里叶变换红外光谱（FTIR），元素分析（CHN），扫描电子显微镜（SEM）和电感耦合等离子体-光发射光谱（ICP-OES）进行表征。FTIR分析表明在pH 3时存在单核柠檬酸铝配合物，在pH 4时存在多核物质。CHN和ICP-OES技术证实了这些结果，揭示了碳，氧，氢，氧化铝沉淀水平随pH的变化而变化。该研究的重点是评估在储层条件下这些交联剂在水凝胶形成中的性能。流变分析表明，柠檬酸铝在pH 6时合成的水凝胶的tanδ值低于0.1，表明凝胶强，而在pH 9时，该值大于0.1，表明凝胶弱。这些结果与通过FTIR获得的结果一致，后者表明在pH 6时，柠檬酸铝配合物的结构可能为[Al 表示强凝胶，而在pH 9时，该值高于0.1，表示弱凝胶。这些结果与通过FTIR获得的结果一致，后者表明在pH 6时，柠檬酸铝配合物的结构可能为[Al 表示强凝胶，而在pH 9时，该值高于0.1，表示弱凝胶。这些结果与通过FTIR获得的结果一致，后者表明在pH 6时，柠檬酸铝配合物的结构可能为[Al₃（C ₆ H ₅ O ₇）₃（OH）₄（H ₂ O）] ^4-。这种结构似乎允许相比于在pH 9合成柠檬酸铝构成的凝胶的铝轨道用于交联过程更容易获得[铝₃（C ₆ H ^ ₆ ö ₇）₃（OH）₄（H ₂ O）₅ ] ⁴⁻。