STUDY ON HIGH - RESOLUTION SEQUENCE STRATIGRAPHY AND SEDIMENTARY MICROFACIES OF Tail - SANDSTONE IN SHA - 1 MEMBER OF THE YANGYING - YANLING AREA

Gaoyang-Yanling area is located north of Lixian Slope, the tail sandstone segment of the lower first member of Shahejie Formation is an important oil producing formation.Based on the theory of high resolution sequence stratigraphy and principles of deposition, integrated previous research papers, combined with the regional geological setting,this paper will use as much information of well logs and cores data as possible to do some research on the source direction, high resolution sequence stratigraphy, sedimentary facies characteristics, the distribution of sedimentary faces of the tail sandstone segment of the lower first member of Shahejie Formation. Innovation and acquaintance acquired from above study were as follows.Through the research of heavy mineral assemblage and lithic component characteristics,combined with the sand thickness distribution characteristics, analysed the orientation of source of the tail sandstone segment of the lower first member of Shahejie Formation in the Gaoyang-Yanling area. Studies suggest that the sediment source mainly comes from north and southwest, southwest direction is the main source direction.Based on the studied type,property,scales and distribution of different base-level cyclics equence surface and flooding surface,the tail sandstone segment of the lower first member of Shahejie Formation is divided into one mid-term datum level and three short-term datum levels, discrpited its structure model, sedimentary series, distribution model. Based on the comparison of the high resolution sequence stratigraphy, established high resolution sequence stratigraphic framework, analyzed the sand body distribution characteristics of the sequence stratigraphy framework.Based on the observation and description of core and a great quantity of logging data,the rock phase and electrofacies were systematically analysised, the rock-electricity response mode which reflects the different sedimentation effect and sedimentary environment was established, On this basis, the types and the characteristics of sedimentary micro-facies were in-depth studied. Studies suggest that the tail sandstone segment in the study area formed in shallow braided river delta-lakes sedimentary system,developed mainly shallow braided river delta front and shallow lake subfacies, underwater distributary channel in shallow braided river delta front is more developed,The mouth bar poorly developed, beach and bar microfacies in shallow lake subfacies is more developed.Through the research of the well facies, connecting-well section phase of high resolution sequence stratigraphic framework,analysed the plane features of the sedimentary microfacies of short-term datum level,summarizes the deposition evolution of the tail sandstone segment of the lower first member of Shahejie Formation in the study area.