Department of Petroleum Engineering, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz, Iran.
Enhanced Oil Recovery (EOR) Research Centre, IOR EOR Research Institute, Shiraz University, Shiraz, Iran.
Sci Rep. 2023 Jul 13;13(1):11337. doi: 10.1038/s41598-023-38428-8.
Smart water injection is one of the engineering techniques to enhance oil recovery (EOR) from carbonate and sandstone reservoirs that have been widely used in recent decades. Wettability alteration and IFT are among the essential and influential mechanisms that can be mentioned to achieve EOR. One of the critical issues in the field of EOR is the effect of reservoir ions on the formation and stability of the emulsion. Investigating the role and performance of these ions during EOR processes is of significant importance. These processes are based on smart water injection and natural production. In this research, stability was investigated and formed during the injection of different concentrations of anionic and cationic surfactants, respectively alpha olefin sulfonate (AOS) and cetrimonium bromide (CTAB), into a water-oil emulsion with a volume ratio of 30-70. Considering the droplet diameter distribution and the flow speed of separation by centrifugation, the optimal concentration level has been investigated in both surfactants. Based on the results, the highest stability and emulsion formation occurred in the presence of AOS surfactant. Then different concentrations of CaCl, MgCl, and NaCl salts were added in optimal concentrations of both surfactants. The formation and stability of the emulsion was checked by examining the distribution of the droplet diameter and the separation flow rate. AOS anionic surfactant had the most stability in the presence of MgCl salt, and better performance in stability of the emulsion was obtained. The maximum number of droplet diameters in the optimal concentration for AOS and CTAB surfactant systems is 1010 and 880, respectively, and for binary systems of AOS surfactant and MgCl, CaCl and NaCl salts, it is 2200, 1120 and 1110, respectively. Furthermore, for the CTAB binary system in the presence of MgCl, CaCl, and NaCl salts, it is 1200, 1110, and 1100, respectively. The stability of the emulsion of salts in the presence of both AOS and CTAB surfactants was MgCl2 > CaCl > NaCl.
智能注水是提高碳酸盐岩和砂岩油藏采收率（EOR）的工程技术之一，近年来得到了广泛应用。润湿性改变和界面张力是实现 EOR 的重要且有影响力的机制之一。EOR 领域的一个关键问题是储层离子对乳状液形成和稳定性的影响。研究这些离子在 EOR 过程中的作用和性能非常重要。这些过程基于智能注水和自然生产。在这项研究中，研究了不同浓度的阴离子和阳离子表面活性剂（分别为α-烯烃磺酸盐（AOS）和十六烷基三甲基溴化铵（CTAB））分别注入油水乳液中时的稳定性，油水乳液的体积比为 30-70。考虑到离心分离时的液滴直径分布和流速，研究了两种表面活性剂的最佳浓度水平。基于结果，在存在 AOS 表面活性剂的情况下，稳定性和乳状液形成最高。然后在两种表面活性剂的最佳浓度下加入不同浓度的 CaCl、MgCl 和 NaCl 盐。通过检查液滴直径的分布和分离流速来检查乳状液的形成和稳定性。在 MgCl 盐存在下，AOS 阴离子表面活性剂具有最高的稳定性，并且在乳状液稳定性方面表现出更好的性能。在 AOS 和 CTAB 表面活性剂体系的最佳浓度下，液滴直径的最大数量分别为 1010 和 880，而在 AOS 表面活性剂和 MgCl、CaCl 和 NaCl 盐的二元体系中，分别为 2200、1120 和 1110。此外，对于存在 MgCl、CaCl 和 NaCl 盐的 CTAB 二元体系，分别为 1200、1110 和 1100。在存在 AOS 和 CTAB 表面活性剂的情况下，盐对乳状液的稳定性为 MgCl2>CaCl>NaCl。
