Commercial helium (He)-rich gas fields have been discovered serendipitously as a by-product of petroleum exploration. As such, the sources of and reasons for the accumulation of He are unclear. In this study, a suite of geochemical diagrams is established to distinguish the three sources of He, i.e., mantle, basement, or sedimentary rocks. The crust-derived He, which is sourced from either basement or sedimentary rocks, is differentiated in view of the diagram of He/N2 ratio versus He concentrations. Based on the geological and geochemical characteristics of He-rich gas in typical natural gas fields, three models of He accumulation in petroliferous basins are proposed, including accumulation of gases rich in magmatic He constrained by deep faults, accumulation of gases rich in crustal radiogenic He in stable cratonic basins, and accumulation of gases with self-generating and self-preserving crustal radiogenic He. He reserves in the main petroliferous basins in China are evaluated at up to approximately 4.792 × 109 m3.

Helium resource in the petroliferous basins in China and its development prospects