HPAM聚合物与离子型表面活性剂协同稳定CO_(2)泡沫的分子模拟研究  

Synergistic effect of hydrolyzed polyacrylamide and ionic surfactant to enhance the stability of CO_(2) foam: A molecular dynamics study

作　　者：贾冀辉 蔡杭 梁云峰 辻健 林梅钦 彭勃[1,2] JIA Jihui;CAI Hang;LIANG Yunfeng;TSUJI Takeshi;LIN Meiqin;PENG Bo(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum-Beijing,Beijing 102249,China;Unconventional Petroleum Research Institute,China University of Petroleum-Beijing,Beijing 102249,China;International Institute for Carbon-Neutral Energy Research,Kyushu University,Fukuoka 8190395,Japan;Department of Systems Innovation,Faculty of Engineering,The University of Tokyo,Tokyo 1138656,Japan)

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石油大学(北京)非常规油气科学技术研究院,北京102249 [3]日本九州大学碳中和能源国际研究所,福冈8190395 [4]日本东京大学工学院,东京1138656

出　　处：《石油科学通报》2023年第1期69-86,共18页Petroleum Science Bulletin

基　　金：国家自然科学基金(U2244208);中国石化海相油气藏开发重点实验室开放基金(33550000-20-ZC0613-0190);国家重点研发计划课题(2018YFB0605501)联合资助。

摘　　要：CO_(2)泡沫驱可以有效地控制CO_(2)相的流度从而提高波及效率,同时它还能够进行CO_(2)地质封存,减少碳排放以应对全球气候变暖的挑战。表面活性剂能降低CO_(2)泡和水相液膜之间的界面张力(IFT),从而增加因拉普拉斯毛细管自吸效应导致的泡沫液膜中液体析出的阻力。聚合物可以提高泡沫液膜黏度,也可以减缓液膜中的液体析出并缓解气泡聚并现象。二者同时被用作提高泡沫稳定性的化学试剂,然而表面活性剂分子根据亲水头基电荷正负属性不同会具有不同的界面行为,在微观尺度下不同类型表面活性剂和聚合物分子之间的协同作用还不明确。本研究采用分子动力学模拟的方法,研究了油藏条件下阴离子型(SDS)和阳离子型(CTAB)表面活性剂分别与水解聚丙烯酰胺(HPAM,水解度25%)在CO_(2)与水相界面处的相互作用。研究结果表明,CTAB比SDS具有更强的降低CO_(2)与水之间IFT的能力,IFT的大小与界面宽度和界面覆盖率呈正相关性。具有相同电性的HPAM与平衡离子Br-在CTAB界面膜上形成竞争吸附关系;而带有相反电性的HPAM与平衡离子Na+在SDS界面膜附近形成盐桥结构。前者更有利于降低气—液界面处IFT和增大液膜厚度,两种模式对泡沫液膜剪切黏度的提高程度差别不大。本研究揭示了阴/阳离子型表面活性剂分别与水解聚合物分子协同作用稳定CO_(2)泡沫的微观机制。CO_(2)foam flooding is an important method at the stage of tertiary oil recovery. It is characterized by dissolving CO_(2)into formation water as a dispersed phase, which can effectively control the mobility of CO_(2), thus increasing the sweep efficiency of displacing phase. Meanwhile, CO_(2)can be stored in the geological formations via the method, mitigating the “Global Warming Effect”. Surfactants can reduce the interfacial tension(IFT) between the CO_(2)bubble and foam liquid film(i.e., water film) hence increasing the resistance to the Laplace capillary suction. Adding polymer can increase the viscosity of the foam liquid film hence retarding the liquid drainage and reducing the bubble coalescence. The two kinds of chemicals are always simultaneously used to stabilize CO_(2)foam in the oilfields. However, surfactants would have different interfacial behaviors due to the different properties of headgroups, and the microscopic mechanisms of interactions between surfactant and polymer molecules at the CO_(2)-water interface are poorly understood. Here, classical molecular dynamics simulations were employed to investigate the influences of charge property(i.e. positively/negatively charged) on the interactions between surfactant and polymer molecules. Sodium dodecyl sulfate(SDS)and cetyltrimethylammonium bromide(CTAB) were selected to represent anionic and cationic surfactant molecules, respectively.Hydrolyzed polyacrylamide(HPAM) with a hydrolysis degree of 25% was chosen to represent polymer molecules. The features of the spatial distribution of the simulated components and molecular arrangements at the CO_(2)-water interface were analyzed, and the relationships between macroscopic properties(such as IFT and viscosity of the foam liquid film) and detailed molecular structure were discussed. The results showed that CTAB is more powerful than SDS in terms of reducing IFT at the CO_(2)-water interface, the variation of IFT values is in good accordance with the changes in interfacial width and interfacial cov

关 键 词：CO_(2)泡沫稳定性 泡沫液膜 表面活性剂 聚合物 界面张力 黏度 分子动力学模拟 

分 类 号：TE357[石油与天然气工程—油气田开发工程]