Layered Structural Deformation Characteristics of Kuqa Foreland Thrust Belt
The seismic data acquired from Kuqa foreland thrust belt is characterized by low signal-to-noise ratio and high interpretive am-biguity.By using high-resolution 3D seismic data,drilling and lab hydrocarbon analysis data,the stratigraphic assemblages of Kuqa fore-land thrust belt were systematically described,the structural model was detailedly interpreted,and the hydrocarbon accumulation system was deeply analyzed.It is found that the Kuqa foreland thrust belt develops two sets of detachment layers:Paleogene and Neogene gypsum-salt rocks,and Triassic and Jurassic coal measures,all of which feature stratified detachment,vertical stacking,and multiphase deforma-tion.Detachment folds in caprocks are found in the shallow structures,while basement-involved imbricate thrust structures are developed in deep strata.Detachment plastic deformation occured in the gypsum-salt and coal layers.Faulting occured in three phases including Cale-donian,late Hercynian-Indosinian,and Yanshanian-Himalayan.The late Hercynian-Indosinian tectonics controlled the Mesozoic sedi-mentation,showing a north-to-south onlap thinning feature.Layered structural deformation in the Kuqa foreland thrust belt governs the stratified accumulation and migration of hydrocarbons.Hydrocarbons in the strata above the coal seam predominantly originated from the Jurassic source rocks,whereas oil and gas in the strata below the coal seam mainly came from the Triassic source rocks which contributs 60%of the hydrocarbons.A substantial quantity of hydrocarbon remains trapped in the formation below the coal layer.
Kuqa foreland thrust beltcoal seamgypsum-salt layerdetachment layerlayered structural deformationstratified hydrocar-bon accumulation and migrationdeep oil and gas