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Chromatograms from the simultaneous use of 2 gas "sniffers," one monitoring hydrocarbon gases and one monitoring H2, while drilling 5 uncased exploratory bore holes in Paleozoic rocks in Kansas substantiates that H2/N2-rich gas emissions are from the sedimentary rocks above the Central North American rift system and are not the result of corrosion of casing pipe. The gases extend over an area of more than 100 mi2, within which they appear to be migrating through formation waters along permeable zones at the silty to sandy base of pyritic shales. H2 was detected in various zones from ±500 ft depth in the Indian Cave Sandstone (Pennsylvanian) to depths of 2,100 ft in the Hunton Limestone (Silurian-Devonian). Negati e peaks (noncombustible), which overlapped the H2 positive peaks on the Wheatstone Bridge chromatograms, are thought to indicate N2 gas. Possible N2 gas occurs from about 1,300 to 2,100 ft, from the Heebner Shale Member (Pennsylvanian) to the Hunton Limestone. H2/N2 peaks on the chromatograms correlate well with the crossover peaks indicative of gas zones on open-hole wireline logs.
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