Characteristics and main controlling factors of helium resources in the main petroliferous basins of the North China Craton

At present, the main controlling factors of helium accumulation is one of the key scientific problems restricting the exploration and development of helium reservoir. In this paper, based on the calculation results of He generation rate and the geochemical characteristics of the produced gas, both the similarities and differences between natural gas and He resources in the Bohai Bay, Ordos and the surrounding Songliao Basin are compared and analyzed, discussing the main controlling factors of helium resources in the three main petroliferous basins of the North China Craton. It is found that the three basins of Bohai Bay, Ordos and Songliao have similar characteristics of source rocks, reservoirs and cap rocks, that’s why their methane resource characteristics are essentially the same. The calculated ⁴He generation per cubic metamorphic crystalline basement in the three basins is roughly equivalent, which is consistent with the measured He resources, and it is believed that the ⁴He of radiogenic from the crust is the main factor controlling the overall He accumulation in the three basins; there is almost no contribution of the mantle-derived CH₄, which suggests that the transport and uplift of mantle-derived ³He carried by the present-day magmatic activities along the deep-large faults is not the main reason for the mantle-derived ³He mixing in the basins. Combined with the results of regional volcanic and geophysical studies, it is concluded that under the background of the destruction of North China Craton, magma intrusion carried a large amount of mantle-derived material and formed basic volcanic rocks in the Bohai Bay Basin and Songliao Basin, which replenished mantle-derived ³He for the interior of the basins, and that strong seismic activities in and around the basins also promoted the upward migration of mantle source ³He. This study suggests that the tectonic zone with dense volcanic rocks in the Cenozoic era and a high incidence of historical strong earthquakes history may be a potential area for helium resource exploration.