Sedimentary Mechanism Of Paleogene Terrestrial Fine-grained Sedimentary Rocks In The NY-1 Well,the Jiyang Depression

Petrographic characteristics and sedimentary evolution models of fine-grained sedimentary rocks are one of the hotspots and difficulties in the study of fine-grained sedimentary rocks at home and abroad,as well as the weak fields of sedimentological research.It is difficult to observe and study fine-grained sedimentary rocks because of their wide distribution range,fine grain size,complex composition,diversity of rocks and so on,and the division boundary of fine-grained rocks is not obvious,so it is very difficult to observe and study the fine-grained sedimentary rocks.The requirements for the laboratory conditions and the accuracy of the experimental equipment are more stringent.Taking the NY-1 well in Jiyang depression as an example,taking the composition of fine grain sedimentary rock as the first factor,on the basis of detailed study of geological data such as core,logging,stratum and so on,this paper adopts the combination of macro and microcosmic,petrology and geophysics,and makes use of the combination of macroscopical and microcosmic,petrology and geophysics.The combination of qualitative and quantitative,field and laboratory research,fine mineral composition image and rock trace element analysis and sedimentary information processing research methods,fusion sedimentology,reservoir geology,petrology,elemental geochemistry,Coal geology,petroleum geology and other multidisciplinary theoretical knowledge,using core observation,micro-slice,scanning electron microscope,element energy spectrum scanning and XRD mineral analysis,etc.,to summarize the sedimentary law of fine-grained sedimentary rocks.The genetic mechanism of fine-grained rocks in the study area is discussed,and the main knowledge is as follows.Based on the analysis of sedimentary stratigraphic evolution characteristics of continental fine grained rocks in Jiyang depression,the horizontal layered gray mudstone facies(FM-1)was identified in the core of the lower Es3 member—upper Es4 member,NY-1 well.Horizontal clayey lamellar mudstone facies(FM-2),horizontal clay lamellar calcareous mudstone facies(FM-3),organic matter striatum and carbonate lamellar interbedded mudstone facies(FM-4),and horizontal clay lamina interbedded calcareous mudstone facies(FM-3),organic matter striatum and carbonate lamina interbedded mudstone facies(FM-4).There are 9 lithofacies:massive limestone facies(FM-5),intermittent clayey lamellar mudstone facies(FM-6),shale facies(FM-7),fine striated siltstone facies(FM-8)and massive mixed facies(FM-9).Combining with the genesis of various lithofacies and the analysis of facies assemblage characteristics of different lithofacies,the sedimentary model of fine-grained rocks in the NY-1 well is established.It is considered that the NY-1 well experienced the climatic change from dry cold to warm wet to relatively warm and wet during the sedimentary period of the lower Es3 member—upper Es4 member in Shahejie formation.The lithofacies characteristics of fine-grained sedimentary rocks have an important influence on the hydrocarbon-generating capacity and reservoir performance of shale,and the analysis of their interrelation with sedimentary environment can also enrich the study of fine-grained sediments.