Characteristics of Chang 9member source rocks and its significance of hydrocarbon exploration in Xingzichuan Oilfield, Ordos Basin

Key words:  source rocks  geochemistry  Chang 9member  Xingzichuan Oilfield  Ordos Basin

Abstract:

By using rock pyrolysis, microscopic examination of kerogen, istope, gas chromatography, GC-MS and other analysis methods, the organic geochemical characteristics of the dark mudstone of Chang 9member in Upper Triassic of Xingzichuan Oilfield in Ordos Basin and its significance of hydrocarbon exploration were studied. The results show that the main source rocks in study area are Lijiapan shale at the top of Chang 9¹, and the geochemical characteristics of the dark mudstone of Chang 9^2show that they are not the petroleum source rocks. The source rocks on Chang 9mainly consist of silty or silt-bearing mudstone, which are not the real clay rocks. The average organic carbon content is 3.05%, and the main kerogen type is type Ⅱ₁, and the average highest pyrolysis peak temperature is 450℃. These show that the source rocks rank is good ones and in the mutual stage. The types of parent materials are characterized by the common input of the lower aquatic organisms and higher plants, and the water environment of lake basin is the fresh water reduction condition as a whole. The comprehensive evaluation shows that Chang 9develops the better hydrocarbon-generating condition, which tends to generate oil. The region whose thickness is over 10m is the favorable exploration target area of Chang 8to Chang 10petroleum accumulations.