Helium surveys in petroleum exploration

Most oil and gas reservoirs concentrate He to some degree and the most He-rich are sources of commercially-available He (Cook, 1979 Voronov et al., 1981). In some oil and gas fields, concentrations of several percent have been recorded (e.g., Boone, 1958 Dyck, 1976), but data summarised by Voronov et al. (1974) show that the average concentration is much lower. 

Jones and Drozd (1983) sampled gases from 4 m depth to reduce the effect of atmospheric equilibration. Over the shallow (60-300 m) Lost Hills oil field in California, USA, they noted that He (and H2) anomalies were present near faults, particularly those penetrating into the basement. They concluded that whereas Hj, together with the light alkanes, appears to be a petroleum indicator. He may be a tectonic indicator, independent of petroleum and gas. 

The He content of waters has rarely been investigated for hydrocarbon exploration. However, Dyck and Dunn (1987) report that broad, coincident anomalies of 2.4 pL/L He and 0.4 pL/L methane in wells and springs in the Cypass Hills district, Saskatchewan, Canada, correlate with commercial oil and gas fields and/or tectonic features. High He concentrations can distinguish thermogenic methane from biogenic methane (marsh gas). 

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