Published 1996 as part of Memoir 66
Copyright © 1996 The American Association of Petroleum Geologists.  All Rights Reserved.
 

The use of population variations in hydrocarbon-utilizing microorganisms as a surface geochemical exploration technique for oil and gas has been vigorously studied since the 1940s. The Microbial Oil Survey Technique (MOST) was developed by Phillips Petroleum Company in the 1950s and held proprietary until 1985. In the development of the methodology, Phillips periodically sampled a particular test traverse over known production near Bartlesville, Oklahoma, beginning in 1957. Geo-Microbial Technologies (GMT) continued to sample the test traverse beginning in 1986. In addition to the yearly sampling, the test traverse was sampled monthly in 1993 by GMT to determine if seasonal variations affect the specific suite of microorganisms measured in MOST. Although slight changes in the absolute microbial concentrations did occur through the seasons, after factoring out oil production effects, the trend in microbial highs and lows across the test traverse remained constant. In the monthly surveys throughout 1993, of all the seasonal and weather factors tracked, only soil moisture content seemed to correlate with the monthly change in absolute microbial counts. Microbial lineplots covering this 37-year period demonstrate the continuous nature of hydrocarbon microseepage over a known hydrocarbon accumulation and the reproducibility of associated microbial prospecting.