Prediction Of Shale Oil Content And Distribution

In this paper,the upper member of the Lower Cretaceous Jiufotang Formation in Ludong depression of Kailu Basin is taken as the research object.Based on the description of shale,the lithofacies of shale is divided by means of rock thin section,scanning electron microscope,QEMSCAN,XRD and other methods.On the basis of geochemical analysis of source rocks,the oil-bearing and mobility of shale are mainly analyzed by means of multi temperature step pyrolysis,successive extraction and other methods.The main achievements of this paper are as follows:The shale thickness centers of the upper ninth member of Ludong sag are distributed in the south,East and north of the sag.Three types of lithofacies(shale,mudstone and fine siltstone)and seven types of fine-grained sediments(felsic shale,dolomitic shale,felsic mudstone,dolomitic mudstone,dolomitic(limestone),tuffaceous shale and siltstone)are identified.There are some differences in sedimentary environment between Sanshifangdi and the upper part of the ninth member of Jiaolige sag,which leads to more cloud rich mudstones and occasional siltstones in Jiaolige sag.From the bottom to the top,there are changes of felsic mudstones,calcareous mudstones,felsic shales,cloud rich mudstones and siltstones;Sanfangdi sag is mainly composed of felsic shale,dolomitic shale and tuffaceous shale.The shale series of Jiufotang formation is characterized by large thickness,wide distribution,high abundance of organic matter,various kerogen types and moderate maturity of organic matter.The shale extracts are characterized by two highs and two lows of salinized Lake Basin,i.e.high saturated hydrocarbon,low aromatic hydrocarbon,high non hydrocarbon and low asphaltene.The content of saturated hydrocarbon in Jiaolige sag accounts for 1/3 of the total extractives,and the content of some layers in Sanshifangdi sag is close to 50%.The characteristics of shale oil resource abundance,shale oil resource and shale oil movable resource distribution in each region of the study area are defined.The oil and gas occurrence mode in the 30 square area is two-stage,the upper part is mainly saturated hydrocarbon,and the lower section is in a large amount of hydrocarbon discharge stage;The oil and gas occurrence in the Jiaolige sag is three-stage,the upper section contains saturated hydrocarbon(shale section),the movable hydrocarbon in the middle section is active,and the lower section enters the high hydrocarbon discharge stage.This paper analyzes the influencing factors of oil-bearing in the upper Jiulong formation from three aspects of hydrocarbon generation potential,reservoir performance and preservation conditions.The overall oil-bearing of the study area is good,and the mobility is medium.The lower limit of oil saturation index is 75 mg/g.According to the plane superposition of main parameters of shale oil evaluation,it is pointed out that the favorable exploration area of jiaolige sag is mainly distributed in the south of jiao41-lucan-2 line,and the favorable exploration area of sanfangdi is located in the center of the sag.