The Study On Sedimentary Microfacies Of Upper Part Of The Fourth Member Of The Shahejie Formation In The Q9-111 Fault Block Of Linnan Slope

In this paper,under the guidance of High-resolution Sequence Stratigraphy,Sedimentology,Field Subsurface Geology and other basic theory,According to the sedimentary background and stratigraphic characteristics of the study area,the upper part(quasi sequence group)of the fourth member of the Shahejie Formation can be divided into four short-term cycles(parasequences),24 ultra-short-term cycles(small layer)through a comprehensive analysis of cores,logs and seismic data;On the basis of a comprehensive analysis of petrology,structural,sedimentary structures,logs,rhythm features and other signs,We can identify that this area mainly develop the fan delta front with the background of shallow,and can be further subdivided 5 kinds of microfacies :underwater distributary channel,overbank sand,mouth bar,front sheet sand,distributary bay et al.Then we make a detailed summary of the various sedimentary microfacies lithology,grain size,sedimentary structures,natural potential curve shape and other characteristics;according to univariate analyzes mapping method,we can use sandstone thickness,percentage of sandstone,logging curves and other parameters to analyze the sand and sedimentary plane distribution characteristics of each stratigraphic group,repeatedly deleveling and swing of distributary channel in the process of longitudinal evolution,sedimentary facies distribution changes accordingly.Based on the microfacies characteristics and vertical evolution,we summary the sedimentary facies model of this region.Based on the above studies,and with the combination of different physical properties of sedimentary microfacies characteristics,we know that: underwater distributary channel and mouth bar microfacies was the dominant reservoir facies;in the process of sedimentary evolution,the active faults can be the main pathways for hydrocarbon migration,and the oil and gas will accumulation under fault and unconformity in the closure period;the interlayer thickness with a good closure.mainly between 2.0 and 5.5m,Taking all these factors into consideration and with the method of multivariate analysis,we carry out favorable objectives forecast with the priority sub-layer that: the traps of this area is mainly associated with the fault block traps,with the second sub-layer of third sand group and the sixth sub-layer of second sand group is most favorable.