Development of a New High-Pressure High-Temperature Technology for Advanced Screening of Biosurfactants and Injection of Microbes in Porous Rocks during Low-Salinity EOR Processes

Abstract

A new high-pressure high temperature (HP-HT) lab-scale rig involving microbial cultivation of pure bacteria strain under reservoir conditions of up to 200 bar and 200°C has been developed. This was accompanied by an extensive laboratory investigation to establish the mechanisms associated with the production and screening of Lipopeptide from pure Bacillus mojavensis NCIMB 13391 strain for the purpose of enhanced oil recovery (EOR) processes. We report for the first time, thermodynamic standard Gibbs free energy required for the Lipopeptide environment friendly biosurfactant (EFBS) formation (ΔGf°) as -2135.1 J.mol−1, and very low brine salinity water (VLBSW) molarity of 0.5096 mg.l− 1. The produced Lipopeptide biomaterial under anaerobic batch cultivation technique generated CMC values of 2.8 mg.l−1 and 2.7 mg.l−1 in deionised water and VLBSW respectively. The dimensionless molecular weight of the produced Lipopeptide biomaterial is 1423.69 and high spontaneity nature of the biomaterial resulting from a more negative ΔGf° value aided the interfacial tension (IFT) reduction of the heavy crude oil and VLBSW system from 15.71 mN.m−1 to 0.04 mN.m−1 at critical micellisation concentration (CMC) of 2.7 mg.l−1 and 65°C under reservoir confined environment, and 1.76 mN.m−1 at 25°C temperature and 55 bar pressure conditions. However, 2.7 mg.l−1 solution molarity, 65°C temperature and 55 bar pressure are recommended as the optimum recovery pilot molarity, temperature and pressure of the screened heavy crude oil material in low-salinity EOR processes.