Comprehensive Review on the Role of Surfactants in the Chemical Enhanced Oil Recovery Process

Abstract

With a constant upsurge in energy demand, production from depleted and harsh reservoirs through enhanced oil recovery techniques (EOR) has significantly increased. Among many EOR techniques, chemical EOR (cEOR) is one of the most widely used methods of oil extraction. Surfactants used in cEOR are instrumental in reducing interfacial tension (IFT) and altering the wettability of rock, which leads to additional oil recovery. This review draws attention to detail on surfactants from fundamentals to field scale. Properties of surfactants like phase behaviors, critical micelle concentration (CMC), hydrophilic–lipophilic balance and deviation, zeta potential, and their importance are discussed in depth. The presence of a saline environment, polymer, cosurfactant, and other factors affecting the performance of surfactant during the cEOR process are also elaborated. Key findings on surfactant adsorption on reservoir rock with other influencing aspects have also been reported in this study. Types of surfactants, from basic to the likes of polymeric, viscoelastic, Gemini, natural, and their effects on oil recoveries have been analyzed and compared. Special emphasis on emerging aids for surfactant flooding such as applications of nanotechnology, use amphoteric Janus particles, and synergies of surfactant–low salinity water flooding, along with their mechanisms and recent advances have been thoroughly duscussed. Lastly, the review delineates discerning criteria for the selection of surfactants, reviews recent field applications, and outlines the challenges that the industry faces while implementing surfactant cEOR. It has been found that exhaustive studies have been conducted on sandstones with success. However, extreme temperature and saline conditions in the case of carbonate reservoirs limit the applicability of surfactants, and the pursuit to accomplish its efficacy continues.

Observation of Strong Synergy in the Interfacial Water Response of Binary Ionic and Nonionic Surfactant Mixtures

“…Surfactants are a special class of amphiphilic organic molecules that have a high surface propensity in solutions of water and other polar liquids. Surfactants also often possess a unique capability of forming supramolecular assemblies among themselves , and with various other molecular systems such as proteins and carbon nanotubes. , The study of the molecular properties of these assemblies has emerged as an important research topic due to their enormous potential in biological, − industrial, , and environmental applications . Motivated by the widespread applications of surfactants, many experimental, − and theoretical studies have been devoted to the understanding of intermolecular surfactant interactions, both in the bulk and at interfaces.…”

Oil Recovery Performance by Surfactant Flooding: A Perspective on Multiscale Evaluation Methods

“…Among the evaluation methods is the oil recovery test, which demonstrates the capability of the potential EOR agent or method to recover the remaining oil from the rock samples. Many recent publications have described the use of surfactants as EOR agents as well as advances in the process. ,,− However, to the best of the authors’ knowledge, most of these publications provide general overviews and analyses of the surfactant EOR process. Additionally, none of them focus specifically on the different techniques implemented to evaluate the oil recovery during surfactant flooding.…”

Molecular dynamics simulation study of adsorption of anionic–nonionic surfactants at oil/water interfaces

“…To enable the better application of oil exploitation, it is necessary to research a new type of surfactant for the complex geological environment. 7,8…”

“…To enable the better application of oil exploitation, it is necessary to research a new type of surfactant for the complex geological environment. 7,8 Compared with anionic surfactants, anionic-nonionic surfactants could effectively solve the above problems caused by high salt and high temperature by designing non-ionic and anionic groups in one molecular structure at the same time. As surfactants for oil repelling, anionic-nonionic surfactants show greater advantages than anionic surfactants, which have led many scientists to use anionic-nonionic surfactants in the petroleum industry.…”