Study On The Source And Migration Direction Of Continental Facies Oil And Gas In The Western Part Of North Tarim Basin

Western Tarim can be divided into general marine facies and continental facies accumulation system.The continental oil and gas are mainly derived from two sets of source rocks of the Jurassic and Triassic in the Kuche depression,arine oil and gas are mainly derived from the middle upper Ordovician source rocks and mainly gathered in the Ordovician system.The continental facies oil and gas in the Western Tarim are mainly distributed in the Paleogene-Cretaceous and Silurian-Ordovician-Cambrian buried hills.The exploration practice has proved that the unconformable surface of the bottom of the Paleogene and the bottom of the Cretaceous system is an important transport channel for Kuche continental oil and gas.In this paper,the typical oil and gas reservoirs in the areas such as Yingmai,Yudong,Yangtake and Quele are selected.The work of sampling research,analysis,data processing and so on has been carried out.Paleogene and Cretaceous are mainly condensate gas reservoirs,carbon isotopes of ethane in natural gas are heavier than-28 per thousand,mainly coal type gas,there are large differences between the maturity of crude oil and natural gas,characteristics with different sources and different periods.Based on the geological background,the reservoir and hydrocarbon accumulation period,combining the characteristics of biomarker,carbon isotope,oil and gas maturity,two types of oil and gas sources in the western part of Tabei are determined.Among them,the oil properties of Yingmai 32 in Cambrian and Ordovician,Yingmai 34-35 in Siluric and and Ying Mai 7-9 multiple oil and gas reservoirs are very similar.They come from the source rocks of the Mount Huangshan Jie group lacustrine source rocks.The crude oil of Quele-Yudong-Yangtake region originates from the lacustrine source rocks of the Jurassic Chuck Mark formation.The source of natural gas is studied by the size of carbon isotopes of natural gas,because it is less affected by maturity and can be used as an important indicator for the study of natural gas sources.Natural gas ethane carbonisotope of yudong-Yingmai is similar and heavy,mainly from the Jurassic Yangxia coalgas.Natural gas ethane carbon isotope of Quele-Yangtake is close and relatively light,as the Chuck Mark group and the associated gas of Jurassic Yangxia coal gas mixture.Through the concentration of nitrogen compounds,methane carbon isotope,gas-oil ratio,aridity coefficient and other geochemistry parameters,the direction of oil and gas migration in the west of northern Tarim has been made clear.