Zhang Jie, Zhao Zhen, Sun Jinsheng, Dong Shengwei, Li Dongyang, Qu Yuanzhi, Zhao Zhiliang, Zhang Tianxiang
CNPC Engineering Technology R&D Co., Ltd., Beijing 102206, China.
CNPC Greatwell Drilling Co., Ltd., Beijing 124011, China.
Polymers (Basel). 2025 Jul 22;17(15):2005. doi: 10.3390/polym17152005.
Surfactants can be utilized to improve oil recovery by changing the performance of reservoirs in rock pores. Kerogen is the primary organic matter in shale; however, high temperatures will affect the overall performance of this surfactant, resulting in a decrease in its activity or even failure. The effect of surfactants on kerogen pyrolysis has rarely been researched. Therefore, this study synthesized a polymeric surfactant (PS) with high temperature resistance and investigated its effect on kerogen pyrolysis under the friction of drill bits or pipes via molecular dynamics. The infrared spectra and thermogravimetric and molecular weight curves of the PS were researched, along with its surface tension, contact angle, and oil saturation measurements. The results showed that PS had a low molecular weight, with an MW value of 124,634, and good thermal stability, with a main degradation temperature of more than 300 °C. It could drop the surface tension of water to less than 25 mN·m at 25-150 °C, and the use of slats enhanced its surface activity. The PS also changed the contact angles from 127.96° to 57.59° on the surface of shale cores and reversed to a water-wet state. Additionally, PS reduced the saturated oil content of the shale core by half and promoted oil desorption, indicating a good cleaning effect on the shale oil reservoir. The kerogen molecules gradually broke down into smaller molecules and produced the final products, including methane and shale oil. The main reaction area in the system was the interface between kerogen and the surfactant, and the small molecules produced on the interface diffused to both ends. The kinetics of the reaction were controlled by two processes, namely, the step-by-step cleavage process of macromolecules and the side chain cleavage to produce smaller molecules in advance. PS could not only desorb oil in the core but also promote the pyrolysis of kerogen, suggesting that it has good potential for application in shale oil exploration and development.
表面活性剂可通过改变储层在岩石孔隙中的性能来提高原油采收率。干酪根是页岩中的主要有机质；然而，高温会影响这种表面活性剂的整体性能，导致其活性降低甚至失效。表面活性剂对干酪根热解的影响鲜有研究。因此，本研究合成了一种耐高温的聚合物表面活性剂（PS），并通过分子动力学研究了其在钻头或管道摩擦作用下对干酪根热解的影响。研究了PS的红外光谱、热重曲线和分子量曲线，以及其表面张力、接触角和油饱和度测量结果。结果表明，PS分子量较低，MW值为124,634，热稳定性良好，主要降解温度超过300℃。在25-150℃时，它能将水的表面张力降至25 mN·m以下，添加盐类可增强其表面活性。PS还使页岩岩心表面的接触角从127.96°变为57.59°，转变为水湿状态。此外，PS使页岩岩心的饱和油含量降低了一半，并促进了油的解吸，表明对页岩油储层有良好的清洗效果。干酪根分子逐渐分解成较小的分子，并产生包括甲烷和页岩油在内的最终产物。系统中的主要反应区域是干酪根与表面活性剂的界面，界面上产生的小分子向两端扩散。反应动力学由两个过程控制，即大分子的逐步裂解过程和提前产生较小分子的侧链裂解过程。PS不仅能解吸岩心中的油，还能促进干酪根的热解，表明其在页岩油勘探开发中具有良好的应用潜力。
