Evaluation of produced volumes of carbon dioxide from the concentration of the gas absorbed in the media during microbial fermentation for enhanced oil recovery purposes

Carbon dioxide produced by microbes during microbial enhanced oil recovery process (MEOR) promotes oil displacement and productivity through re-pressurization of the oil field and dissolution of the rock matrix. In the laboratory studies conducted using an adapted strain of Clostridium tyrobutyricum (DSMZ 663) in fermentation media of 500 mL, the volume of the produced gas, the concentration of the dissolved gas determined using titrimetric method and pH of the media as a result of microbial metabolic activities at different salt concentrations (0, 30, 60, 90 and 100 g/L) were measured after 24, 72 and 120 h. The volume of produced gas decreased from about 3000 mL at 0 g/L to 250 mL at 100 g/L. The rate of absorption, volumetric mass transfer coefficient and partial pressure were then related quantitatively as a function of salinity and were compared. The result shows that the rate of absorption decreases exponentially with salinity suggesting a strong correlation with R² value of 0.75-0.98 at constant coefficient of 0.0002. The volumetric mass transfer coefficient for carbon dioxide at 0 g/L is approximately 6 times greater than at 100 g/L suggesting the influence of the salinity of the media. The correlation of the gas concentration in the solution with the gas bulk volumes produced at different salinities after 120 h (R ² = 0.97) suggests an accurate tool for the estimation of the amount of gas produced by microbes.