Experimental Investigation of Potential of Combined Controlled Salinity and Bio-Surfactant CSBS in Enhanced Oil Recovery EOR Processes

Abstract

In this study, we investigate potential application of environment-friendly bio-surfactants (EFBS) in EOR processes. We assess the prospect of combining the EFBS with controlled salinity (CS) water injection in optimising oil recovery using rhamnolipid and protein-enzyme as case study. Rock component analysis, bio-surfactant solubility in brine of varied concentration and composition, crude oil-brine interfacial tension (IFT) and bio-surfactants emulsification activity test were carried out as part of the preliminary investigations. Following these preliminary analyses, a series of comprehensive core flooding displacement experiments were used to investigate the EOR potential of CSBS injection process. Finally, effluent analyses were conducted to study the effect of this combined process on dynamic oil-brine-rock interactions. Results of the IFT tests using 0.0083-3M brine concentrations show IFT reduction from 3.40-2.5 mN/m with increasing salinity for protein-enzyme while increase in IFT from 0.11-0.34mN/m was observed with increasing salinity for rhamnolipid. However, using a fixed brine concentration of 8.3mM with varied bio-surfactant concentration, IFT reduction with increase in concentration was observed for both of them. Also, the two bio-surfactants exhibited stable emulsion active in varied brine salinity investigated. Protein-enzyme is soluble in varied brine formulation while rhamnolipid solubility was found to be dependent on the brine composition and system pH rather than the ionic strength. Furthermore, from the secondary injection of CS and CSBS, the highest recovery factor of 82.76% was achieved with CSBS (protein-enzyme). However, in the tertiary applications, the highest recovery of 83.40% was achieved in the CS injection. Finally, increased pH, Ca2+ and Mg2+ concentrations was observed with both CS and CSBS flooding. This suggests reaction between excess cations and previously adsorbed carboxylic group of crude-oil led to increased recovery. Whereas, at residual oil saturation, interaction between bio-surfactant molecules and rock surface resulted in increased water-wetness and release of oil.

A Synergy between Controlled Salinity Brine and Biosurfactant Flooding for Improved Oil Recovery: An Experimental Investigation Based on Zeta Potential and Interfacial Tension Measurements

“…The results are consistent with the spontaneous imbibition at similar conditions and indicate the ability of CSB and biosurfactants to shift the wetting state of rock sample towards being more neutral (i.e., initially oil-wet rock samples became less oil-wet when using these solutions). Furthermore, the results of this study show that CSB imbibition increases oil recovery relative to FMB but the process was accompanied by apparently emulsified oil production, which is consistent with the core flooding experiments carried out by Udoh et al [34]. This suggests the possibility of formation of microdispersion of micelles [18] or rock dissolution [45,46] during CSB displacement process.…”

“…Also, the use of CSBS-G and CSBS-R increases oil recovery relative to FMB and CSB applications with CSBS-R process being characterised by fastest imbibition rate. This effect is attributable to its high surface activity that enhances oil-brine IFT reduction and increase in capillary effect [34,38].…”

“…Hence, there has been increased research on biologically generated surfactants (biosurfactants) as substitute for chemical surfactants and studies have reported the biosurfactants to be as efficient as chemical surfactants in different applications [27]. Also, past studies have reported EOR potential of biosurfactants (e.g., [22,[28][29][30][31][32][33][34]) but effect of biosurfactants on zeta potential of CORB system has not been explored. The main objective of this study, therefore, is to investigate the potential of synergy between CSB and biosurfactants for further improvement of oil recovery and to investigate their effect on rock-fluid interactions.…”

Experimental Investigations of Behaviour of Biosurfactants in Brine Solutions Relevant to Hydrocarbon Reservoirs

“…Greenzyme is a water soluble protein-enzyme produced using DNA of selected oil-eating microbes [11,24]. Greenzyme has not been extensively studied, although there are some recent studies (e.g., [13,25]) on its EOR applications but limited studies have been reported on its physicochemical properties.…”

Rapid screening of oil-rim reservoirs for development and management

“…reservoirs in the Niger Delta and elsewhere (John et al 2019;Elharith et al 2019;Ogolo et al 2018;Olabode et al 2018;Udoh et al 2018;Obinna et al 2016). For simplicity, both the porosity and K v /K h remain unchanged for all the cases investigated.…”