The Study On Characters Of Organic Geochemistry And Sedimental Environment Of Source Rocks From Taipinglinchang Formation In Sunwu-Jiayin Basin

Sunwu—Jiayin Basin is located in the three towns of Sunwu, Jiayin and Xunke in Heilongjiang Province,which is south edge of the Jieya—Bulieya basin. The whole basin is divided by the Heilong river, the area of which reachs 55000km2. Besides, the part in China reachs 22810km2. The Cretaceous system is the main sedimental layer in this basin. Taipinglinchang formation in upper Cretaceous is the most important source rock layer, in which the indications of oil and gas in the sandstone interlayer among mudstone was found by DaQing oil field.The cross section belongs to the lower Taipinglinchang formation are measured and drawed. The upper section of the lower Taipinglinchang formation exposes near the LuoBei highway and the bottom section exposes at the side of Heilong river.We sampling and do some testing. The studys on the organic petrology indicate the high content of aspropel+exinite; the strong fluorescent display under the blue-light source excitzting fluorescent light; some of samples containing the low-mature micro component, such as suberinite and spore, which have the latent capacity of generating low-mature oil; The studys on organic geochemistry of source rocks demonstrates the high abundance of organic matter. For example, the total content of organic carbon ranges from 0.111% to 3.399%, the effective carbon content 0.015%～0.57%, the latent content of generating hydrocarbon S1+S2 0.04mg/g～11.07mg/g, chloroform asphalt"A"from 0.0009 to 0.0273%. The characters of high non-hydrocarbon content in the chloroform asphalt"A"and non-hydrocarbon inverting hydrocarbon are similar with the characters of low-mature source rocks in many important oil and gas basin.The results of organic element analysis and the carbon isotope analysis indicate the organic types are type- II, III, some type-I, showing the good organic types.The vitrinite reflection Ro range from 0.55% to 0.92%, indicating the immature-low mature source rock.All of these indicate the soure rocks are middle-good. Besides, the black mud stone with the big thickness, the high ratio in stratum and small thickness of per layer are is for generating, discharging and migrating.The studys on solvable component demonstrate the normal alkanes form the most ourcrop samples show double peaks; the predominance of high carbon homologen.CPI and OEP indicate the character of low mature. The majority of samples from the wells show the mature source rock and the predominance of the low carbon homologen. The ourcrop samples Pr/Ph range from 0.68 to 2, indicating the character of fresh water–low salt water lake in reductive circumstance; the samples Pr/Ph from Jia D2 well range from 0.06 to 1.4, indicating the character of salt water lake in stronge reductive circumstance. The content distribution of terpane reflects the tendency of quadriterpaneC28