Mountains Region In The Ordos Basin, Yanchang Sedimentary Microfacies And Sequence Stratigraphy Study

Based on current exploration and production data in Zhongshanchan area of Ordos Basin, and sufficiently absorbed predecessors'findings, this paper Comprehensively utilizes geophysical and geochemical means to systematically study sedimentary micro-facies types, distribution of sedimentary facies and characteristics of sequence stratigraphy of Chang6 oil formation of Zhongshanchuan area, under the guidance of high-resolution sequence stratigraphy.On the basis of stratigraphic classification of Upper Triassic in Ordos Basin. Combined with key bed, lithologic character and electric property character, cycles of sedimentation, etc,Chang6 oil formation is divided into three subzone:Chang6i,chang62,chang63.Based on the study of facies indicators of sedimentary structure, Biological characteristics and geophysical signature,Chang 6 oil formation is a delta sedimentary system, including delta plain and delta front. Delta plain can be divided into distributaries channel and inter distributaries channel, delta front can be divided into distributaries channel underwater, interdistributary, mouth bar etc.Combining with previous research, based on the basic Principles and ways of high-resolution sequence stratigraphy, the paper identifies the short term, medium term and long term base-level cycles, and divided the Chang4+52—chang6 oil formation into 8 short term,3 medium term and 2 long term base-level cycles.After correlating each of the base-level cycles, the high-resolution sequence stratigraphic framework of Chang 6 formation is defined.