Isolation, characterization, and metabolism of microorganisms indigenous to subterranean oil-bearing formations.

摘要

The overall objective of this research was to develop information on the microflora indigenous to subterranean oil reservoirs, with special emphasis on its potential role in microbial enhanced oil recovery (MEOR).; To accomplish the above stated objective, the following studies were performed: (a) to quantify and characterize the microbial species indigenous to several different oil-bearing formations, (b) to determine the ability of microbial isolates to utilize various carbon and nitrogen sources and identify by-products that may be useful in MEOR processes, (c) to determine whether sulfate-reducing bacteria are indigenous to petroleum reservoirs, (d) to determine whether ultramicrobacteria are indigenous to petroleum reservoirs, and (e) to determine the ability of indigenous microorganisms in intact cores to grow with the addition of supplemental nutrients.; A total of seven intact cores were obtained for use in this research. Reservoir depth from which the cores were obtained ranged from 805 ft to 14,596 ft. It was shown that all seven cores contained viable microorganisms and ultramicrobacteria were found in two of the seven cores. No sulfate-reducing isolates were obtained even though the literature reports this type of organisms as the most prevalent in oil reservoirs.; Of the large number of pure culture isolates obtained from the seven cores, 97 were retained for morphological and cultural characterization, of these, 37 were tested for their ability to utilize various carbon and nitrogen sources. Results showed that the indigenous microflora of the oil reservoirs either as a pure or as a mixed microbial cultures can and will grow under anaerobic conditions and will produce substances useful in recovering oil (gases, acids, emulsifiers, solvents, and polymers). The cultures also colonized stratal materials to produce by-products of importance in MEOR.; Core flooding experiments revealed that, the addition of supplemental nitrate ions and orthophosphate ions to the injection water resulted in an increase in microbial numbers, the production of gases, and the production of acids in the effluent from the cores. These events were synchronized with release of the fine particles and the release of oil from the core.; The results of this investigation support the concept that microorganisms indigenous to oil-bearing formations may be of valuable in enhancing oil recovery if properly supplied with supplemental nutrients to produce sufficient quantity of by-products. In this era of heightened environmental awareness, it is important to note that no adverse environmental effects will results from either using the supplemental nutrients or producing the microbial by-products.