HYDROCHEMICAL CONDITIONS AND NATURAL GAS ACCUMULATION IN THE MIDDLE PART GASFIELD OF THE ORDOS BASIN

The author systematically evaluates the organic geochemical characteristics of five sets of hydrocarbon source rock series in the Bachu Uplift of the Tarim Basin, studies the distributive features of organic facies for the carbonate and argillaceous source rocks of various strata in plane and section, and discusses the oil/gas sources of the Bachu Uplift. The results show that the major hydrocarbon source rocks of the strdy area are the Cambrian-Ordovician high-mature marine carbonate source rocks in the deep part, while the Carboniferous marine and terrigenous mixed source rocks take second place. The oil and gas mainly comes from deep source rocks of the study area. It is clear that the oil-generating contribution of the east is greater than that of the west, and the contribution of the north is greater than that of the south. Meanwhile, there is the Carboniferous crude oil migrated laterally from the Southwest Depression.