Models of helium enrichment in helium-rich gas reservoirs of petroliferous basins in China

Abstract

Owing to the characteristics of chemical inertness, low molecular weight, low boiling point, strong permeability and high heat conductivity, helium is extensively used in the fields of aerospace, low-temperature superconductivity, medicine and high tech, and it is a kind of irreplaceable strategic rare resource. So far, however, less research has been conducted on the enrichment of helium in natural gas reservoirs. To solve this problem, this paper discusses the classification standard of helium-rich gas reservoirs. Based on this, the origin, source and enrichment process of helium in typical helium-rich gas reservoirs are studied, highlighting the contribution of main helium sources to helium-rich gas reservoirs. In addition, helium enrichment models of helium-rich gas reservoir in petroliferous basins are established. And the following research results are obtained. First, 6 helium enrichment models of two categories (crust-source helium enrichment and crust-mantle mixing helium enrichment) are established for different petroliferous basins in China. Second, helium-rich gas reservoirs are characterized by using the multiple helium supply and diverse helium enrichment model. And no matter what enrichment model it is, the contribution of the main helium source to gas reservoirs is indispensable. Third, the helium in the gas reservoirs of central and western basins is mainly crust-source helium, and its enrichment models include ancient formation water moving upward along the fault to dilute helium, helium enrichment in the process of natural gas migration along ancient reservoirs, and helium enrichment of shale gas. Fourth, the helium in the helium-rich gas reservoirs of eastern basins is of crust-mantle mixing origin and its enrichment models are mainly hydrocarbon gas based, carbon dioxide based and nitrogen based. In conclusion, the establishment of the helium enrichment models of helium-rich gas reservoirs in petroliferous basins provides reference and guidance for studying helium enrichment laws and main controlling factors and is of great significance to the evaluation of favorable helium exploration areas.