Abiogenetic natural gases in songliao basin and their exploration prospects

It is shown by geochemical characteristics that the natural gas reservoirs containing a great number of carbon dioxide, which were found in Songliao Basin everywhere, belong in abiogenetic ones, and the hydrocarbon gas, found at Xujiaweizi region and being of heavy carbon isotope and reverse carbon isotopic series, indicates that in the basin there are not only abiogenetic carbon dioxide gas reservoirs but the abiogenetic hydrocarbon gas reservoirs probably exist. The research results of deep basin geology reveal that Songliao Basin possesses the conditions of forming abiogenetic gases because of mantle arching, crustal attenuation and developed net structure and discordogenic faults in the crust, and that the abiogenetic natural gases found in the basin may be originated from the deep part of the earth. The fluids developed in various spheres and layers in the earth interior are the foundation of forming abiogenetic natural gases. In Songliao Basin, both sides of the ancient central uplift belt and the western depression are the favourable areas of forming abiogenetic natural gases and the discordogenic fault belt along Nenjiang River and mantle source magma diapirism belt are the beneficial areas of prospecting for abiogenetic hydrocarbon gases.