Carbon dot nanomaterials (<10 nm) exhibit superior application prospects as oil displacement materials for unconventional reservoir development. However, the limited oil–water and oil–solid interfacial activity of carbon dot nanomaterials restricts their broader application. In this study, carbon dot nanomaterials (CDs) are expeditiously prepared via a microwave-assisted synthesis method utilizing urea and citric acid as precursor compounds. OAB-modified active carbon dot nanomaterials (OCDs) are prepared by grafting oleic acid amidopropyl betaine (OAB) through hydrothermal reaction at 90 °C for 5 h using CDs as a carbon dot carrier. Stability experiments show that the plentiful hydrophilic groups present on the surface of the OCD augment electrostatic repulsion among them, thereby imparting dispersibility, temperature tolerance (90 °C), and salt resistance (2.6 × 10⁴ mg/L). Additionally, OCDs demonstrate optimal effectiveness at a concentration of 0.5 wt %. At this concentration, OCDs can reduce the interfacial tension to 0.66 mN/m and achieve the underwater oil contact angle to 126°. Within 24 h, OCDs can strip 60.6% of the oil film. OCDs show the excellent ability to enhance oil–water and oil–solid interfacial activity. Meanwhile, OCD nanofluids can effectively form emulsions with crude oil and spontaneously demulsify within 2 h in a state. Core flooding tests demonstrate that OCD nanofluids, when compared with simulated formation water, reduce injection pressure by 46.3% and enhance oil recovery by 31.1%. This study offers a promising solution for the efficient development of unconventional reservoirs with carbon dot nanomaterials.

中文翻译：

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用于非常规油藏开发的高界面活性碳点纳米材料

碳点纳米材料（<10 nm）作为非常规油藏开发的驱油材料表现出优越的应用前景。然而，碳点纳米材料有限的油水和油固界面活性限制了其更广泛的应用。在这项研究中，利用尿素和柠檬酸作为前体化合物，通过微波辅助合成方法快速制备碳点纳米材料（CD）。以CDs为碳点载体，通过90℃水热反应5 h，接枝油酸酰胺丙基甜菜碱（OAB）制备OAB修饰的活性碳点纳米材料（OCDs）。稳定性实验表明，OCD表面存在大量的亲水基团，增强了它们之间的静电排斥力，从而赋予其分散性、耐温性（90℃）和耐盐性（2.6×10 ⁴ mg/L）。此外，OCD 在 0.5 wt% 的浓度下表现出最佳效果。在此浓度下，OCD可以将界面张力降低至0.66 mN/m，并使水下油接触角达到126°。 24 小时内，OCD 可以剥离 60.6% 的油膜。 OCD表现出优异的增强油水和油固界面活性的能力。同时，OCD纳米流体可以有效地与原油形成乳状液，并在2小时内自发破乳。岩心驱油试验表明，与模拟地层水相比，OCD 纳米流体可降低注入压力 46.3%，提高采收率 31.1%。这项研究为碳点纳米材料非常规油藏的高效开发提供了一种有前途的解决方案。