塔里木盆地叠合演化与油气聚集

Superimposition,evolution and petroleum accumulation of Tarim Basin

根据前人成果和石油勘探资料,对塔里木盆地进行了解剖,认为自寒武纪以来,它经历了寒武纪—志留纪—泥盆纪、石炭纪—二叠纪、三叠纪—侏罗纪、白垩纪—新生代等四大构造演化阶段。寒武纪—泥盆纪盆地演化阶段受周缘板块裂离与汇聚的控制,以碳酸盐岩、膏盐岩和碎屑岩建造为特征,盆地基底整体由早期的西高、东低向东高西低翘倾转变,中奥陶世末的构造事件形成了沙雅、塔中和塔西南古隆起,志留纪晚期的构造事件导致了盆地的整体隆升与剥蚀。石炭纪—二叠纪进入陆表海盆地和陆内坳陷演化阶段,以碳酸盐岩和膏泥岩建造为主要特征,整体表现为西南降、东北抬的构造格局。二叠纪沉积末的构造事件导致了盆地隆升与剥蚀,北部构造变形、剥蚀强烈。三叠纪形成了南、北山前坳陷和台内坳陷盆地,侏罗纪沉积主要在山前坳陷。自白垩纪—古近纪,盆地整体沉降,发生了海侵,逐渐形成大型陆内坳陷盆地,白垩纪末构造事件导致了巴楚隆起的初步形成和地层的剥蚀,新近纪晚期的构造事件形成库车、塔西南前陆盆地和中央隆起带。盆地叠合演化形成了中-下寒武统、中-上奥陶统、三叠系-侏罗系等多套富含有机质的烃源岩,与盆地内叠合联片发育的中-下寒武统膏泥岩、上奥陶统泥岩、石炭系膏泥岩、三叠系-侏罗系泥岩、煤系和古近系-新近系膏盐岩、泥岩构成了盆地内最佳的源盖组合,成为油气富集的基础。碳酸盐岩岩溶储层、碎屑岩中的砂岩储层与构造作用形成的圈闭形成了盆地良好的储-圈组合,成为油气富集的必要条件。盆地的多期叠合演化形成了台盆区下组合、中组合和山前坳陷区上组合三大勘探层系。勘探成果显示,古隆起、古斜坡和烃源岩的分布控制盆地内油气分布。

According to previous research and petroleum exploration data,Tarim Basin has experienced four evolution stages： the Cambrian-Devonian faulted basin,the Carboniferous-Permian basin,the Triassic-Jurassic intra-continental basin and the Cretaceous-Cenozoic large basin. The evolution of the Cambrian-Devonian basin was controlled by the peripheral plates splitting and convergence and was characterized by clastic,evaporite and carbonate build-ups. The basement had a structural pattern of west uplifting and east depressing from the Cambrian to Ordovician. The Late middle Ordovician tectonic events lead to the formation of the Shaya uplift,Tazhong uplift and Hetian paleo-uplift. The Late Silurian tectonic events led to the uplift and erosion of the basin as a whole. The Carboniferous- Permian basin was characterized by epicontinental sedimentary and intra-continental depression evolution of carbonates,gypsum-salt and clastic rocks. The basement had a structural pattern of southwest depressing and northeast uplifting in this stage. At the end of Permian,tectonic events led to the uplift and erosion of the basin. In the Triassic,the southern and northern piedmont depression and an intra-platform depression were formed. The Jurassic basin only existed on the front tectonic belt. From the Cretaceous to Paleogene,the Tarim gradually formed a large-scale intra-continental basin. The sea water invaded Basin again. At the end of Late Cretaceous,tectonic events led to the demise of the basin and the overall uplifting. The Late Cretaceous deposits were limited in the southwest and east Tarim. Kuche and southwest Tarim foreland basin formed because of tectonic event of the Late Neogene. Evolution of the superposed basins led to the formation of several sets of organic-rich source rocks,such as the Lower-Middle Cambrian,Middle-Upper Ordovician,Triassic,Jurassic. The gypsum,salt,mud and coal-bearing rocks developed in the Cambrian,Ordovician,Carboniferous,Triassic,Jurassic,Paleogene and Neogene are good seals.These seals and source rocks consist of high-quality combination within the basin. Carbonate karst reservoirs and sandstone reservoirs and the structural traps consist of favorable reservoir-trap combinations. The lower,middle and upper assemblages are favorable sequences for exploration in the basin. Exploration results show palaeohigh,paleoslopes and ancient source rocks control oil and gas distribution of the basin