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Forming Mechanism Of Hydrocarbon Reservoirs In The Ordovician Carbonate Rocks And Triassic Clasolites Of Yuqi Block In Northern Tarim Basin

Posted on:2008-04-21Degree:DoctorType:Dissertation
Country:ChinaCandidate:L X KuangFull Text:PDF
GTID:1100360215998862Subject:Mineral prospecting and exploration
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Oil & gas reservoiring is mostly the analysis of hydrocarbonreservoirs characters, forming process of hydrocarbon reservoirs and oil& gas distributing rule. It is not only one of the basic theoretical researchfields of petroleum geology, but also one of the focal points in the studyof petroleum geology and the key problems existing in petroleumexploration and exploitation. The Tarim basin is a typical superimposedpetroliferous basin in NW China. It is believed that petroleum system inthis basin is hybrid. Taking Yuqi block as an example which is animportant oil & gas exploration play in the surroundings of Tahe oilprovince in Akekule arch, Tarim basin, the reservoir types and itsdistributing rule, preservation conditions, oil & gas accumulationconditions, accumulation process and accumulation periods in themiddle-lower Ordovician Yingshan Formation carbonate rocks andTriassic clasolites are studied, oil & gas accumulation models areestablished, key control factors of oil & gas accumulation and oil & gasdistributing rule are summarized, and the best prospecting plays areevaluated by using the techniques of basin analysis, reservoir prediction,fluorescence thin section and fluid inclusion, the failure analysis oftypical exploration well, typical oil & gas reservoirs anatomy andintegrated geology analysis under the guidance of the theories of basinformation, hydrocarbon generation, and oil & gas accumulation.By using the techniques of Log interpretation, seism reservoirprediction and reservoir integrated study, reservoir types of in themiddle-lower Ordovician Yingshan Formation carbonate rocks andTriassic clasolites are analyzed. The carbonate reservoirs are of cave,fracture-pore and fracture types, and their physical properties arerelatively poor. Large Karst cave and fracture and pore in core developsufficiently in the mid and western part of Yuqi block, and developrelatively poor in eastern part of Yuqi block, but cave and fracture andpore filling is very compact. The favorable reservoirs are located in theWell Yq3 and Well Yq4 blocks. The clasolites reservoirs's porosity is high, their permeability is intermediate to high, and their physical propertiesare mostly controled by sandstone sort and diagenesis and sedimentaryfacies. The favorable reservoirs are located in the central part of Yuqiblock where the Well YQ3, the Well YQ4, the Well LX4 and the WellLX2 are.According to the lead line of the structure evolution history and oil &gas migration and accumulation history, the oil & gas carrier beds arestudied part by part in Yuqi block by using the fluid potential theory. It isdemonstrated that the resource abundance in Yuqi block is very lowbecause of Akekumu fault barrier in the southern part of Yuqi block.The technique of fluid inclusion analysis together with fluorescencethin section analysis was established, oil & gas accumulation process andaccumulation periods in the middle-lower Ordovician YingshanFormation carbonate rocks and Triassic clasolites of Yuqi block werestudied on the basis of core observation and under the guidance of thetheories of oil & gas accumulation. The study results indicate that thereare at least four oil/gas charges, i.e., late Hercynian, Yanshanian, earlyHimalayan and middle Himalayan in Yingshan Formation; there are atleast three oil/gas charges, i.e., Yanshanian, early Himalayan and lateHimalayan in Triassic clasolites.Oil & gas accumulation new models in Yingshan Formation and inTriassic are established, key control factors of oil & gas accumulation andoil & gas distributing rule are summarized by using Oil & gas sourcecorrelation, fluorescence thin section and fluid inclusion analyses,analysis on the failure of typical exploration well and typical oil & gasreservoirs anatomy. The oil & gas accumulation model in YingshanFormation is self source-lateral expulsion of hydrocarbon-multistageaccumulation, or hydrocarbon sourced from and preserved in the sameold rocks-long term expulsion of hydrocarbon-multistage accumulation,and its evolution has four stages. The accumulation model in Triassic isoutward source-bidirectional expulsion of hydrocarbon-multistageaccumulation or hydrocarbon sourced from the old rocks and preservedin the new rocks-bidirectional expulsion of hydrocarbon-multistageaccumulation, and its evolution has two stages. The preservation conditions, for example seal rocks, are an primaryfactor of controlling hydrocarbon distributing and accumulation, and theoil & gas source conditions are an important factor in YingshanFormation. Tectonic traps and faults are an primary factor of controllinghydrocarbon distributing and accumulation, and the oil & gas sourceconditions are an important factor in Triassic.By using method of integrated geology evaluation, the middle-lowerOrdovician Yingshan Formation carbonate rocks and Triassic clasolitesof Yuqi block are evaluated, and the best prospecting plays are evaluated.The best prospecting play in Yingshan Formation is located in thesoutheastern part of Yuqi block where the upper Ordovician cover themiddle-lower Ordovician, and the Well YQ8 tectonic trap which islocated in the southeastern part of Yuqi block is the best prospectingtarget. The best prospecting play in Triassic is located in the central southpart of Yuqi block where the Well YQ4 and LN13 are, and the Well GP5tectonic trap which is located in the best prospecting play of Yuqi block isthe best prospecting target.
Keywords/Search Tags:fluorescence thin section, fluid inclusion, the forming of hydrocarbon reservoirs, accumulation model, Akekule arch
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