Sedimentary Characteristics And Distribution Of Turbidite Sand Body From The Third And Fourth Sections Of Shahejie Formation In Niuzhuang Subsag

Turbidity sandstone is of great importance in subtle reservoir exploration. To guide oil exploration and development in turbidite of study area better, the paper hackles genetic features and distribution rules of turbidity Sandstone in faulted basin in the larger sense on the basis of regional geologic setting. The paper also detailedly studies specific regions(Wang 58 well,Dongke 1 well) of turbidity sandstone of depression belt and gentle slope belt during deep faulted depression in Niuzhuang Sag, and summarizes main controlling factors and evolution laws of turbidity sandstone development, finally offering deployment suggestions for exploration and development.Based on review and summary of tuibidity sandstone study, through synthetical consideration of dynamic mechanism and distribution characteristics of gravity flow and by combining actual conditions of continental rift basin with operability principles, turbidite deposit of Jiyang Depression during deep faulted depression can be divided into 3 genetic types: fan near shore, fan off shore and slump turbidite fan. Through systematically analyzing microscopic distribution of turbidity sandstone,differences in development types and distribution characteristics of turbidity sandstones can be found among different structural belts on the plane.For Wang 58 well located in gentle slope belt of Niuzhuang Sag, off-shore turbidite fans develop in Sha4 upper Member,extending along SE-NW direction and reflecting a process that water power becomes weaker vertically.Change of lake level, source recharge and structural gradient are main factors affecting the form and development of turbidity sandstone. For Dongke 1 well located in depression belt of Niuzhuang Sag, turbidity sandstone of this area belongs to LST of 3-order sequence of Sha3 intermediate member, extending from southeast to northwest with two branches in forms of subaqueous alluvial fan and deep-water turbidite fan and forming superimposed model of sedimentary facies assemblages, sequence and system tract on the section. The allocating relationship,”source-slope-depression”, controls types and characteristics of turbidity sandstones.Through overall cognition of turbidity sandstone reservoir in continental lacustrine basin and analysis of the case, it can be concluded that the main factors controlling development of turbidity sandstone are tectonic movement, paleoclimate, sediment supply and changes of lake level. Furthermore, the thesis analyzes development laws and patterns of the turbidity sandstones under different controlling factors systematically. Finally regarding the above research as guidance and combined with the practice of a certain study area, the paper provides deployment recommendations for the exploration and development of turbidite reservoir.