A Study Of High-resolution Sequence Stratigraphy And Sedimentary Characteristics Of Single Sand-body Of The Third Member Of Palaeogene Shahejie Formation In The Guan15-2Block Of Wangguantun Area, Huanghua Depression

This paper focuses on the Es3oil layers in the guan15-2fault block,under theguidance of high-resolution sequence stratigraphy theory and the correspondingtechnological methods and on the basis of what have been achieved, we establish thehigh-resolution isochrohal stratigraphic frame by studying core data, logging data,well logging data, seismic data fully, then study the sedimentary system with thisframe. According to the leading line of “high-resolution stratigraphy layers-sedimentary systems-sequence lithofacies paleogeography map–analysis of singlesand-body”,we analyse the types and the changing character of sedimentary faces,sedimentary subfacies, sedimentary microfacies, and defined the distribution of thesedimentary system, finally establish the sedimentary model. We also pay specialattention to the study of the distribution of single sand body:firstly, we analysethe sedimentary microfacies characterizes of every single sand-body. Secondly, weanalyse the characteristics of the top micro-structure of single sand-body byapplying the division results of single sand body. Finally, we have the followingresults:1.Through the comprehensive studying of the high-resolution sequence character,Wecarry out the level division of high-resolution sequence and separate the ES3oillayers of the study area into four medium-term cycles: MSC1, MSC2, MSC3,MSC4;We also carry out the high-resolution sequence stratigraphy isochronous contrast of ES3oil layers,at the same time,and establish the correspondinghigh-precision sequence stratigraphic framework. Finally we convertone-dimensional strata and lithofacies information into three-dimensionalinformation.2．Through the analysis of the core and well logging data, combined with thesedimentary faces, we make clear the fact that the ES3oil layers formed in thelacustrine delta environment which belong to the lake sedimentary background. Inthe study area, it’s only developed the delta front subfacies. From the analysis of thesedimentary character, there are subaqueous distributary channel, debouch bar, distalbar in this area. These microfacies developed throughout the whole study area.3.In MSC1-MSC4periods, the delta front subfacies occupies the majorpositions. Subaqueous distributary channel mainly distributes in the MSC1risingphase, distal bar distributes in the MSC1decline phase and MSC2period; thecarbonate beach bar which mainly forms by the bioclastic beach microfaciesdistributes in the top area of MSC2decline phase. From MSC1to MSC4,sedimentary microfacies evolve from subaqueous distributary channel to thedebouch bar to the distal bar, and this process reflected it’s transgressive in thatperiod.4.We define38single sand-body through separating and comparing the singlesand-bodies in the ES3oil layers. On the basis of this result, we define themicrofacies of every single sand-body in the mid-sequence frame by referring theprevious sequence-sedimentary facies and sand-bodies distribution maps and finallyachieve38maps. We also take into account of single sand-body and itssequence-sedimentary facies and sand-bodies distribution maps, make clear thestructure of every single sand-body. Finally we have38top micro structure featuremaps of the single sand-bodies.