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 optimizing 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.
Picture: I investigated solubility of GreenZyme and another bio-surfactant in different salinity concentration and composition and found GreenZyme to be soluble in all solutions. Maximum concentration investigated is 3M, while the other bio-surfactant precipitated in some solutions.The first three tubes are the examples of the other bio-surfactant behavior in solutions with the first tube showing its precipitation while the other two show its solubility in solution. The last three tubes on the other hand shows GreenZyme solubility in solutions of the same electrolyte composition as used for the other sample.
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. GreenZyme (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.