Selection Method of Activator for Indigenous Energized Microorganisms in Daqing Oilfield with Low Permeability Reservoirs

In recent years, microbial enhanced oil recovery methods have been systematically applied in the Daqing oilfield in order to stimulate and increase oil production, remaining difficult to be recovered after polymer flooding. In this paper, a selection method of activator for indigenous energized microorganisms in Daqing oilfield with low permeability reservoirs was proposed. Firstly, the number of microorganisms in samples taken from production and injection wells in the target block was measured. Based on the obtained results, the condition for the use of MEOR method in the studied well system was determined. Secondly, laboratory experiments were conducted on the culture of indigenous microorganisms and the optimal parameters of the activator for indigenous microorganisms was determined by the obtained experiment results. Thirdly, the concentration of indigenous microorganisms, the pH value, interfacial tension, the viscosity change of the crude oil and the amount of generated gas after the hydrocarbons metabolization were measured. Based on the values of the crude oil viscosity and the amount of generated gas, the optimal ratio of nutrients (glucose and corn steep liquor) that are part of the activator for indigenous microorganisms was determined. The experimental results showed that when the ratio of nutrients (glucose and corn liquor) is equal to 1:2, the viscosity of the crude oil after the activation is minimal and the amount of generated gas after the hydrocarbons metabolization reaches the maximum value. The selected activator composition was used to culture indigenous microorganisms in samples taken from production wells in the studied well system. The pressure increase was observed due to the occurrence of biogas during the process of hydrocarbon degradation by microorganisms. In the further development of the Daqing field with low permeability reservoirs using microbiological methods, it is recommended to use the selected activator composition for the culture of indigenous microorganisms.