Abstract: This invention provides methods and systems for prospecting for subterranean oil and gas deposits by detecting the presence of hydrocarbon-consuming microorganisms in soil samples taken from a field of interest for production. A preferred method of this invention comprises suspending and diluting each soil sample in mineral salt solution, combining the sample with a selective growth, substrate such as an alcohol or aldehyde, and an oxidation-reduction dye in a gas-tight tube, incubating the sample and measuring the color change of the dye. Advantages of this system include: results obtained in short times (24 to 72 hours), substantially eliminates false positives, accurate results particularly when a spectrophotometer is used to measure the color changes, and it is automatable with computer controlled systems for processing samples, reading the color changes and calculating and plotting test results.

Abstract: In a polymer flood, where bacterial contamination frequently causes a loss in viscosity of the polymer, the viscosity of the polymer solution is maintained by the use of a xanthan polymer modified by methylation of a portion of the subunit sugar residues of the xanthan base.

Abstract: A process for the production of a storage-stable preparation of micro-organisms, starting from a mixed culture of micro-organisms, which is capable to degrade products of industrial organic syntheses, which comprises that the culture conditions of an active mixed culture enriched in the customary manner are optimized, with the addition of the product to be degraded, in the customary manner according to the rate of degradation of the product and this mixed culture is converted in at least two passes into a stabilized activated mixed culture under the optimum conditions thus determined, and the culture thereby obtained is rendered storage-stable, its activity being maintained.