Isolation and identification of efficient viscosity - reducing microbes for enhanced recovery of heavy oil
Student name: Ms Farzana Kolyariwala
Guide: Dr Ramakrishnan Sitaraman
Year of completion: 2010
Host Organisation: Microbial Biotechnology, TERI
Supervisor (Host Organisation): Dr Banwari Lal
Abstract: Heavy petroleum is an important energy resource, but is difficult to exploit due to the dominant heavy constituents such as asphaltenes. They are known for clogging wells, flowlines, surface facilities and subsurface formations. In this study, viscosity reduction of Jodhpur heavy oil has been carried out by the degradation of asphaltenes using Enterobacter aerogenes, Clostridium sp and Garciaella sp. These microorganisms produce gases (H2, CO2) and acids (acetate, butyrate) that mobilize the oil trapped in reservoirs and improve oil recovery. The bacterial growth was monitored in TG medium with asphalt fraction as a carbon source along with molasses over a period of 30 days for production of gases and volatile fatty acids at 45°C and 50°C. Amongst the microbes tested, TERINB7 (Clostridium sp) at 45°C and TERIG02 (Garciaella sp) at 50°C produced maximum H2 (51.09 mmol/L; 38.22 mmol/L), CO2 (72.18 mmol/L; 68.18 mmol/L), acetate (1349 mg/L; 743mg/L) and butyrate (354 mg/L; 186 mg/L) resulting in maximum viscosity reduction by 42% and 37% respectively over the control. The viscosity reduction by asphaltene degradation has been further structurally characterized by Fourier Transform Infrared Spectroscopy. This is possibly the first report on viscosity reduction by asphaltene degradation under anaerobic conditions by microbial means. The results demonstrate significant reduction in viscosity of heavy oil by bacterial means and are indicative of the potential of microbial treatment as a viable substitute for conventional methods employed in viscosity reduction.
Keywords: asphaltene degradation, viscosity reduction, Fourier Transform Infrared Spectroscopy, gases (H2, CO2) , volatile fatty acids.
