摘要/Abstract
通过调控原油-岩石界面润湿性进而提高采收率是油田高效开发的重要思路. 现有阴离子表面活性剂改变岩石表面润湿性能力有限, 研发强化界面润湿调控性能的新型驱油剂具有重要应用意义. 本工作合成了一种新型表面活性剂二羟甲基十二烷基苯磺酸钠(SDDBS), 通过红外和核磁进行结构表征. 探究了SDDBS在亲油岩石表面的吸附行为、降低油水界面张力能力、对岩石表面润湿性调控能力、油膜剥离能力以及驱油性能. 实验结果表明SDDBS可在亲油岩石表面均匀吸附, 临界胶束浓度下可将油水界面张力降至2.54 mN/m, 亲油玻璃片经0.02% (w) SDDBS溶液处理48 h后, 其空气中水滴接触角由100.2°降低至24.5°, 水下油滴接触角由19.2°增加至153.9°, 证明SDDBS可将亲油/疏水的岩石表面调控为强亲水/水下强疏油状态. 采用0.02% (w) SDDBS溶液在60 ℃下处理原油老化的玻璃片, 24 h内油膜剥离面积高达89%, 在地层水条件下油膜剥离面积仍可达81%. 室内模拟岩心驱油实验结果显示采收率提高10.53%. 本工作通过一步法合成一种新型多羟基苯磺酸盐驱油剂, 通过引入氢键强化其界面润湿调控能力用于油膜高效剥离, 具有较强实际应用潜力.
关键词: 表面活性剂, 驱油剂, 界面润湿性, 油膜剥离
Controlling the wettability of the oil-rock interface is an important way for highly efficient oilfield development. For existing anionic surfactants, their capability of changing the wettability of the rock surface is limited. Therefore, developing novel oil displacement agent with enhanced interfacial wettability control capability is of great significance. In this work, an interfacial wettability controlling oil displacement agent, sodium dimethyloldodecyl benzene sulfonate (SDDBS), was synthesized and the structure was characterized by Fourier transform infrared (FT-IR) and 1H-nuclear magnetic resonance (1H NMR). The critical micelle concentration (cmc) of SDDBS was measured by spinning drop method and was determined as 0.02% (w). The adsorption behavior of SDDBS on oil-wet rock surface, the interfacial tension reduction property, wettability controlling property, oil film peeling performance and the oil displacement performance were evaluated. Based on the atomic force microscopy (AFM) images, SDDBS could adsorb uniformly on the surface of oil-wet rocks. The oil/water interfacial tension could be reduced to 2.54 mN/m under cmc. After immersing the oil-wet glass sheet in 0.02% (w) SDDBS solution for 48 h, the contact angle of the glass sheet towards water drop in air reduced from 100.2° to 24.5°, while the contact angle towards oil drop underwater increased from 19.2° to 153.9°, proving that SDDBS could regulate the wettability of the oil-wet/hydrophobic rock surface to strong hydrophilic/underwater oleophobic state. The oil film peeling performance of SDDBS was evaluated by calculating the remaining oil film area by graphical analysis software. When soaked in 0.02% (w) SDDBS solution at 60 ℃, the area of oil film could be reduced by 89% within 24 h. The oil film reduction rate could still reach 81% in simulated formation water, indicating good reservoir adaptability. Laboratory simulation core displacement experiments were conducted at 60 ℃ and the results showed that the oil recovery rate was increased by 10.53%. In this work, a novel polyhydroxy benzene sulfonate surfactant was synthesized by one-step method. By introducing hydrogen bond to enhance the interfacial wetting control ability of surfactant, the oil film could be peeled off efficiently, exhibiting strong practical application potential.
Key words: surfactant, oil displacement agent, interfacial wettability, oil film peeling off
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