黄龙天然气田富氦地质条件与成藏模式

he Ordos Basin has the properly geological conditions in helium-rich natural gas, which has high helium resource potential. But the Huanglong Gas Field (hereinafter referred to as "Huanglong Gas Field") lacks an in-depth analysis of the geological conditions, formation process and mechanism of helium. Based on literature research, core logging, logging analysis, natural gas component and isotope testing, this paper has evaluated the geological conditions of Huanglong gas field and then establishes a helium formation model. The results showed that the helium content in Huanglong Gas Field is high in the south and low in the north, with a peak helium content of 0.226% in the south and 0.168% in the north. The helium content decreases gradually to the east and faster to the west. There are crystalline metamorphic basement and the high uranium and thorium abundance in mudstone and bauxite formations , which are presumed to be potential helium source rock. The basement fracture , the widespread reverse faults and the tectonic fractures are all advantageous channels for helium transportation. The abundant stratigraphic water and pore water provide migratory carrier for helium transportation. There are well confined cap layers such as mudstones, muddy carbonates, muddy hard gypsums, also there are regional cap layers with high residual pressures. In conclusion, the mode of helium reservoir formation is helium degassing from the groundwater. The understanding of helium distribution and mechanism of helium formation in Huanglong Gas Field in this paper has certain theoretical value and practical significance for helium exploration and development in Ordos Basin.