Analysis on Helium Enrichment Characteristics and Reservoir Forming Conditions in Northwest Tarim Basin

As a widely used non-hydrocarbon noble gas, helium has been frequently detected in natural gas out of oil and gas reservoir, many of which has reached or exceeded the industrial standard. Considering the comprehensive utilization of helium, we analyzed the helium enrichment characteristics and reservoir forming conditions in northwest Tarim basin. The drilling and test data showed that the content of helium in natural gas was higher in Yakela, Shaxi 2, Bashituo and Ysongdi, and helium accumulated as concomitant of natural gas. It was stored in Lower-Ordovician, Upper Carboniferous, Lower Permian and Lower Cretaceous, and mainly concentrated in the high part of structural traps and the top of reservoir. The helium was mainly from the crust, and a small amount of them was from the mantle. The volcanic activity in Lower Permian supplied a rich source of helium, and the deep faults provided a channel for helium to migrate upward. The good sealing condition was to the benefit of accumulation and preservation of helium.