When the reservoir pressure drops the oil field dries up though there is a lot of oil. To pump out the remains one has to apply pressure by pumping into the oil-bearing bed water or gas. Other method – to apply biotechnology. The oil is contaminated with specially bred mi-croorganism strains, which produce gas, acids and surface active agents (SAA) as the results of methabolism. The gas pressurises of the oil-bearing bed, and SAA ease the oil viscosity. This biotechnological method is very expensive for Russia, because the microorganisms must be fed up with the sugar production waste. Dr. Beliaev S.S. from the Microbiology Institute of ASR suppose that the natural biocenose of the oil-bearing bed is also usefull under correct treat-ment.
There are three microorganism groups in the oil: hydrocarbonoxidating, methhanogens, sulphate deoxidising. The first and the second are useful. They generate CO2, methane and SAA. Also, the first produce the food for the second. To gain their number the oxygen satu-rated water with mineral additions should be pumped into the oil-bearing bed. The aerobic hy-drocarbonoxidating mikroorganisms will rapidly grow, producing food for anaerobic meth-hanogens and the products of both metabolism drive the oil up.
But the third group of microorganisms is detrimental. They generate the sulphates, which are capable of disabling the drilling equipment. If there are a lot of detrimental microorganisms in the oil-bearing bed or the pumped water is salt then this method is inapplicable.
The proposed method has been tested in The Tatarian, The Bashkirian, Azerbaijan and West Siberia oil-mines. It has been shown that the feeding of natural microflora aids to en-hance the oil recovery in 10 – 40 %.
Chemistry and Life – XXI century. August 1999.