Study Of Sedimentary Fades Characteristic Of Shahezi Formation-the First Section Of Quantou Formation In Xiaochengzi Area Of Songiiao Basin

This article largely and widely collects forerunners’ data. Based on the systemsanalysis of drilling, logging and seismic data of Shahezi formation-the first Sectionof Quantou formation in Songliao Basin, this study has detailed stratigraphic divisionand correlation of target formations, and the research area has5sedimentary faceswhich includes lacustrine face,fan delta face, sublacustrine fan face, braided river faceand meandering river face,10sub-face and26micro-face.On this basis, combined with the distributing feature of sand body and seismicfacies, the study establishs the distributing feature of sedimentary faces of eachformation and gives four kind of sedimentary systems of Shahezi formation-the firstsection of Quantou formation in the research area,which includes semi-deep lake-fandelta-sublacustrine fan sedimentary system, semi-deep lake-fan delta sedimentarysystem,(shore) shallow lake-fan delta-sublacustrine fan sedimentary system andbraided river and meandering river sedimentary system.Base on the comprehensive analysis of sedimentary facies distribution of eachstratigraphic unit which belongs Shahezi formation-the first section of Quantouformation, the study gives the structure-sedimentary evolution features during thesedimentary period of Shahezi formation to Quantou formation.In the period of the first section of Shahezi formation, the edge of thebasin-controlling fracture has strong activity. The area which is adjacent to thebasin-controlling fracture has rapid subsidence and forms semi-deep lake-fan deltasedimentary system which is smaller but deeper. In the period of the second section-third section of Shahezi formation, basin-controlling fracture has less stronger activity,but the settlement becomes stronger in whole region and the range of sedimentary isexpanding, forming a relatively stable semi-deep lake-fan delta sedimentary system.During the period of second section-third section of Yingcheng formation, the activityof basin-controlling fault has significantly receded. The settlement becomes less stronger in the basin and the water in lake becomes shallow, forming a shallow lake-fan delta sedimentary system. In the period of Denglouku formation, the edge of thebasin-controlling fracture has week activity. The settlement has significantly receded.The terrain gradually becomes flat and the scope of deposition gradually expands. Theshore shallow lake–fan delta deposition system which is in the period of Dengloukuformation gradually transforms to braided river deposition system which is in theearly period of the first Section of Quantou formation, and then to the meanderingriver depositional system which is in the late period.