CHARACTERISTICS,DISTRIBUTION AND SIGNIFICANCE OF PALEOZOIC TYPICAL MARINE SAND BODIES IN THREE MAJOR BASINS IN WESTERN CHINA
The Tarim Basin,Ordos Basin,and Sichuan Basin are the three major oil and gas-bearing ba-sins in western China,rich in oil and gas resources and encompassing extensive exploration areas.Among them,marine-origin terrigenous clastic sand bodies are one of the key targets for oil and gas exploration.Based on previous research,this paper characterizes the features and distribution of typical Paleozoic ma-rine sand bodies in these three major basins and elaborates on their petroleum geological significance.The study results indicate that there are four main types of marine sand bodies developed in the three major ba-sins of western China:(1)Shoreline Sand Bodies:Typically developed near barrier-free coastlines,prima-rily influenced by wave and coastal current dynamics.These sand bodies have well-sorted and well-rounded clastic particles,with typical washout stratification,mainly found in the Devonian Donghetang Formation of the Tarim Basin and the Cambrian Xinjie Formation of the Ordos Basin.(2)Tidal Sand Bodies:Formed in coastal environments with barriers,primarily controlled by tidal action.These sand bodies exhibit typi-cal tidal stratification,mainly found in the Silurian Kepingtage Formation of the Tarim Basin and the Benxi and Taiyuan Formations of the Ordos Basin.(3)Shelf Sand Bodies:Mainly developed in shallow marine shelf environments,influenced by ocean currents and storm surges.They are characterized by sig-nificant sedimentary thickness and good reservoir performance,primarily found in the Permian Benxi,Taiyuan,and Shanxi Formations of the Ordos Basin and the Silurian Shiniulan Formation of the Sichuan Basin.(4)Turbidite Sand Bodies:Mainly developed in semi-deep to deep-sea environments,formed by deep-sea turbidity currents.These sand bodies typically have high porosity and permeability,making them excellent reservoirs,mainly found in the Ordovician Queerquek Formation of the Tarim Basin.These four types of marine clastic sand bodies are extensively developed and widely distributed across different strati-graphic levels in the three basins,forming excellent oil and gas reservoirs.Systematic research on the ma-rine clastic sand bodies in the Paleozoic of the three major basins has significant tectonogeological,paleo-geographical,paleoceanographical,and petroleum geological implications.This research has important theoretical significance and practical value for deepening the understanding of the petroleum geological sig-nificance of marine clastic sand bodies.
Tarim BasinOrdos BasinSichuan BasinPaleozoicGenesis of Marine Clastic Sand BodyGeological Significance
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