High-resolution Sequence Stratigraphy Research Of Es₄² In Damintun Depression

This thesis mainly researches sequence stratigraphy of fine grain sediments in Damintun Depression. In combination with the practical situation of the study area and climate, using the theory of high-resolution sequence stratigraphy and △logR divide sequence stratigraphy of fine grain sediments. On this basis, the sedimentary lithology are analyzed in the study area. Then considering hydrocarbon source rock, reservoirs and brittleness, we predicted tight oil “sweet spots”.This research divide Es₄² into one middle cycles（MSC1）, two short-term basal level cycles SSC1、SSC2. Rising cycle of SSC1, drop cycle of SSC1 and rising cycle of SSC2 correspond to the traditional tight reservoir. On the basis of sequence stratigraphic classification, the study found that during the sedimentary period of oil shale in Anfutun^Jinganbao area, the watery environment is quiet and the tectonic setting is an isolated shallow platform. In this period, climate is relatively hot and dry, and chemistry condition of water is mainly about the reducing environment of micro salt water-brackish water. The seasonal climate changes with the evaporitic environment of drought. According to the study, the causes of shale section（fine grained sediment section） and neritic facies shale genetic types are similar. Under the background of this deposit, SSC1 drop cycle is characterized by rich in dolomitic rocks, and these dolomitic rocks often form in dry and hot climate. Comparing with the high abundance ratios of the rising cycle of SSC2 and rising cycle of SSC1, drop cycle of SSC1 has relatively low organic abundance and the type of diversification. During the period of drop cycle of SSC1, Ⅰ^Ⅲ type organic matter all have a certain amount of development. Rising cycles of SSC1 have the best reservoir and the better brittleness; dropping cycles of SSC1 have the better reservoir and the best brittleness; the reservoir and brittleness in the rising cycle of SSC2 are poor.Combined with hydrocarbon source rock and reservoir research found that sweet spots in rising cycle of SSC1 is Ⅰ and Ⅱ, mainly distributed in AnFuTun, Jinganbao structure. Under the impact of hydrocarbon source rock in rising cycle of SSC1 and rising cycle of SSC2, drop cycle of SSC1 is Ⅰsweet spot, and distributed in Jinganbao area, Anfutun area, and most parts of Shengdong Depression. Most parts of area in rising cycle of SSC2 is Ⅰsweet spot, around the well shen 278, well an 61 and well an3 is mainly Ⅱ sweet spot.