GEOCHEMISTRY AND EVALUATION OF UPPER PALEOZOIC SOURCE ROCK ON YIMENG UPLIFT,ORDOS BASIN

Source rock founds the basis for hydrocarbon generation and is of significance to determination of the resource potential in the exploration area. This paper is devoted to the lithology, thickness and geochemical characteristics of the Upper Paleozoic source rock in the Yimeng Uplift belonging to Ordos Basin. The Upper Paleozoic source rocks in the Yimeng Uplift are mainly consisting of dark mudstone, carbonaceous mudstone and coal of the Taiyuan and Shanxi Formations. According to the statistics, the total thickness of the Upper Paleozoic dark mudstone in northern Ordos Basin ranges from 10 to 50m while the total thickness of coal is between 2 and 25m. Hydrocarbon source rocks in the southern and eastern parts of the Yimeng Uplift are thicker than those in the northern and western parts, and the quality of source rocks seems better in some depressions than that in other areas. Carbonaceous mudstone and coals in the Taiyuan and Shanxi Formations are relatively high in organic matters, dominated by the Type Ⅲ of Kerogen followed by the type Ⅱ. The original organic matter is supposed to be deposited in an aerobic environment. Ro value ranges from 0.6% to 1.8%, suggesting that the source rock has entered a matured or high matured stage. The amount of gas generated by the Upper Paleozoic source rock in the southern part is larger than that produced in the northern part of the Yimeng Uplift. The results of the study may provide a basis for hydrocarbon evaluation of the Upper Paleozoic in the Yimeng Uplift.