  Citation: Gbadamosi, A.; Patil, S.; Kamal, M.S.; Adewunmi, A.A.; Yusuff, A.S.; Agi, A.; Oseh, J. Application of Polymers for Chemical Enhanced Oil Recovery: A Review. Polymers 2022, 14, 1433. https://doi.org/10.3390/ polym14071433 Academic Editor: Marta Otero Received: 28 February 2022 Accepted: 28 March 2022 Published: 31 March 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). polymers Review Application of Polymers for Chemical Enhanced Oil Recovery: A Review Afeez Gbadamosi 1 , Shirish Patil 1, *, Muhammad Shahzad Kamal 2 , Ahmad A. Adewunmi 2 , Adeyinka S. Yusuff 3 , Augustine Agi 4 and Jeffrey Oseh 5 1 Department of Petroleum Engineering, College of Petroleum and Geosciences, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia; a.gbadamosi@kfupm.edu.sa 2 Centre for Integrative Petroleum Research, College of Petroleum and Geosciences, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia; shahzadmalik@kfupm.edu.sa (M.S.K.); ahmadade@kfupm.edu.sa (A.A.A.) 3 Department of Chemical and Petroleum Engineering, Afe Babalola University, Ado-Ekiti PMB 5454, Nigeria; yusuffas@abuad.edu.ng 4 Department of Petroleum Engineering, School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310, Malaysia; aaagi2@live.utm.my 5 Department of Petroleum Engineering, School of Engineering and Engineering Technology, Federal University of Technology, Owerri PMB 1526, Nigeria; jeffrey.oseh@futo.edu.ng * Correspondence: patil@kfupm.edu.sa Abstract: Polymers play a significant role in enhanced oil recovery (EOR) due to their viscoelastic properties and macromolecular structure. Herein, the mechanisms of the application of polymeric materials for enhanced oil recovery are elucidated. Subsequently, the polymer types used for EOR, namely synthetic polymers and natural polymers (biopolymers), and their properties are discussed. Moreover, the numerous applications for EOR such as polymer flooding, polymer foam flooding, alkali–polymer flooding, surfactant–polymer flooding, alkali–surfactant–polymer flooding, and polymeric nanofluid flooding are appraised and evaluated. Most of the polymers exhibit pseudo- plastic behavior in the presence of shear forces. The biopolymers exhibit better salt tolerance and thermal stability but are susceptible to plugging and biodegradation. As for associative synthetic polyacrylamide, several complexities are involved in unlocking its full potential. Hence, hydrolyzed polyacrylamide remains the most coveted polymer for field application of polymer floods. Finally, alkali–surfactant–polymer flooding shows good efficiency at pilot and field scales, while a recently devised polymeric nanofluid shows good potential for field application of polymer flooding for EOR. Keywords: polymer; rheology; polyacrylamide; biopolymer; enhanced oil recovery; hydrophobically associating polyacrylamide 1. Introduction After the application of primary and secondary recovery, the literature suggests huge volumes of oil remain in a reservoir [1]. The remaining oil-in-place is the target of enhanced oil recovery (EOR). Hence, EOR methods are used for recovering bypassed and residual oil in the reservoir [2,3]. The devised EOR methods are majorly classified into thermal and nonthermal EOR. Thermal EOR is unsuitable for reservoirs with huge depths, thin pay zones, or underlying aquifers. This is because of high heat loss to overburden and underburden layers [4]. More importantly, the application of thermal EOR is limited due to huge concerns associated with large emissions of greenhouse gases which can lead to global warming and climate change [5]. Hence, nonthermal EOR has received prodigious attention for the recovery of conventional and heavy oil. Chemical EOR, a nonthermal EOR method, has been proffered to improve oil recovery due to its ease of application and high efficiency. Several chemicals such as alkalis, surfac- tants, nanoparticles, and polymers have been utilized for EOR [6–9]. The chemicals tune Polymers 2022, 14, 1433. https://doi.org/10.3390/polym14071433 https://www.mdpi.com/journal/polymers