Fuel xxx (xxxx) xxx Please cite this article as: Taher Al-Ghailani, Fuel, https://doi.org/10.1016/j.fuel.2020.119432 0016-2361/© 2020 Elsevier Ltd. All rights reserved. Full Length Article Application of a new bio-ASP for enhancement of oil recovery: Mechanism study and core displacement test Taher Al-Ghailani a , Yahya M. Al-Wahaibi a, * , Sanket J. Joshi b, c , Saif N. Al-Bahry c, d , Abdulkadir E. Elshafe d , Ali S. Al-Bemani a a Department of Petroleum and Chemical Engineering, College of Engineeering, Sultan Qaboos University, Oman b Central Analytical and Applied Research Unit, College of Science, Sultan Qaboos University, Oman c Oil & Gas Research Center, Sultan Qaboos University, Oman d Department of Biology, College of Science, Sultan Qaboos University, Oman A R T I C L E INFO Keywords: Biosurfactant Biopolymer Interfacial tension Core food ABSTRACT The evaluations of Alkaline-Biosurfactant-Biopolymer (ABsBp) fooding for enhancement of oil recovery appli- cations were explored. A lipopeptide biosurfactant (surfactin) and a biopolymer (schizophyllan) in combination with alkali (Na 2 CO 3 ) were experimentally investigated to evaluate the possibility for EOR studies using native Omani reservoir cores and Berea core plugs. The selected oil reservoir was high permeability (500–1000 mD) sandstone type, the reservoir temperature of 50 ◦ C, and less than 80% water cut. The crude oil was also procured from the selected Omani reservoir, having 27.15 API. The interfacial tension (IFT) values of 0.02–0.1mN/m were observed at comparatively lower biosurfactant and alkali concentrations. The effect of other chemicals and biosurfactant on biopolymer was also studied on its viscosity at reservoir temperature, and no adverse effect was observed on biopolymer performance in the presence of alkali and biosurfactant. The injection of a 0.5 PV slug of 1.1% (w/v) Na 2 CO 3 , 20% (v/v) biosurfactant (400 ppm) and 20% (v/v) biopolymer (600 ppm), followed by 3 PV of biopolymer (600 ppm) drive showed 14% and 32% of additional oil recovery from reservoir cores and Berea cores respectively. This is the frst report of Alkali-Biosurfactant-Biopolymer application using surfactin and schizophyllan, showing additional oil recovery from Omani reservoir cores and Berea sandstone cores. 1. Introduction Petroleum reservoirs produce about one third to one half the original oil in place, leaving behind large quantities of oil which are the target of different Enhanced Oil Recovery (EOR) techniques [1]. Several EOR methods exist and are implemented all around the world [2–7], and Microbial EOR (MEOR) is one of those methods that rely on microbial products such as, biosurfactants, gases, bioacids, solvents, biopolyers, and/or microbial biomass to be utilized in mobilizing the left behind oil [8–11]. MEOR showed its potential to be an attractive option in several cases as a tertiary recovery method as it is touted as cheaper than its alternatives, the injected fuids cost does not depend on oil prices, and products are biodegradable, hence it is an environmentally friendly method [12,13]. It does not present a novel mechanism in EOR, rather bioproducts that could enhance oil recovery correspond to chemicals that are already used in chemical EOR. In other words, replacing syn- thetic chemicals such as surfactants and polymers, with bioproducts produced by microorganisms that would result in enhanced oil recovery by the same mechanisms. MEOR differs from chemical EOR only in means of the source of chemicals and the way they are introduced to the reservoir [14]. Chemical EOR techniques aim to decrease interfacial tension and alter wettability using surfactants and alkalis. Chemical injection could also lead to a formation damage, which could be avoided by nanofuid (such as nanosilica) injections [15,16]. While the mobility control process is done in water fooding by adding small amounts of high molecular weight, water soluble polymers that increase viscosity of the injected brine to improve sweep effciency [5,17]. Biosurfactants can be a good and feasible replacement for the expensive chemical surfactants in enhancing oil recovery; hence continuous research is ongoing to explore the ability of different mi- croorganisms in the production of biosurfactants, which could be eff- cient in harsh reservoir environments [18,19]. Lipopeptide biosurfactants such as surfactin and lichenysins, produced by the Ba- cillus group of bacteria have been reported to be successful in MEOR * Corresponding author. E-mail address: ymn@squ.edu.om (Y.M. Al-Wahaibi). Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel https://doi.org/10.1016/j.fuel.2020.119432 Received 8 July 2020; Received in revised form 15 September 2020; Accepted 5 October 2020