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The application of integrative gas geochemistry combined with mass spectrometry and the use of pattern recognition procedures, has enabled rapid characterization of microseepages of gases along faults and fractures. This has been accomplished by incorporating the activated carbon/Curie point wire collector in gas geochemical surveys of faulted and fractured structures which serve as conduits to the subsurface. Studies conducted in the Denver-Julesburg basin of Colorado, Green River basin of Wyoming, the hingeline of Utah, and the Las Animas arch of Colorado all produced fault-related samples where higher (< C7) molecular weight components were encountered. The results of these fault-associated anomalies have been related to differing organic sources of vario s samples and may be correlated to areal distribution of the source leakage.
When using the analytical technique in relatively unfractured and unfaulted sedimentary rocks, the mass spectra generated typically indicates the presence of compounds containing up to seven carbon atoms. In dealing with fault samples affiliated with producing areas of petroleum, components with masses up to 150 have been analyzed. The Denver-Julesburg basin, Green River basin, and the Las Animas arch studies were all performed in relation to producing oil and gas fields. Although the results from the first three studies were not insignificant, those associated with the hingeline study have a much greater impact toward the potential of exploration application. Through this study, it was discovered that fault leakage not only changed with differing sources of the organic gases and vapo s, but also appears to change with lateral proximity between the sample and the zone overlying the organic source. From these interpretations, an exploration model which utilizes fault leakage as a parameter will be discussed.
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