塔里木盆地沙雅隆起形成演化与油气分布规律

Formation and Evolution of the Shaya Uplift and Constraints on Oil and Gas Distribution in the Tarim Basin

沙雅隆起是塔里木盆地重要的油气聚集单元,有关隆起结构、演化及其对油气藏控制的认识始终存在争议。本文通过全区钻井资料的分析和地震资料解释,进行了地质编图,对复杂油气藏分布规律和控制因素进行了解剖,明确了关键构造事件和隆起的演化特征。研究证实,隆起经历了寒武纪-奥陶纪沉积古隆起、志留纪-白垩纪构造古隆起和新生代埋藏古隆起三大演化阶段,发生了多期构造事件,形成了多个不整合面。志留系沉积前的构造事件导致了雅克拉断凸的形成,断凸区成为志留系的物源区。东河砂岩-石炭系沉积前的构造事件在隆起南部形成了英买力、哈拉哈唐、阿克库勒、草湖等背、向斜,形成了凹、凸结构,并形成了近南北向、北东向、北西向和东西向的断裂。古近纪的弱伸展-剪切作用导致了老断层的重新活动,在盆地浅层形成了一系列雁列构造,使隆起复杂化。新近纪以来的翘倾作用导致了隆起区三叠系以来的地层向北倾伏。隆起的南北分带和纵向分层特征控制了油气的分布,形成了两个油气聚集带、一个油气聚集区。纵向上形成了深部与碳酸盐岩地层相关油气藏和浅层与断裂、低幅度构造、地层不整合、岩性等相关的油气藏。浅层油气藏一般位于深层碳酸盐岩大型油气藏的上部,为次生油气藏。油气藏的形成除了受烃源岩分布、断裂、褶皱、隆起、不整合等因素控制外,碳酸盐岩岩性的溶蚀性差异也导致了油气成藏的复杂性。

The Shaya Uplift is an important oil and gas accumulation unit in the Tarim Basin. There is controversy on the tectonic evolution and factors controlling hydrocarbon accumulation. In this paper, remnant strata distribution of the pre-Carboniferous is identified by the analysis of drilling cores and seismic data. The key tectonic event and uplift evolution are confirmed. The complex oil and gas reservoir distribution and its control factors are discussed. The uplift experienced many tectonic events and formed multiple strata unconformities. There are different tectonic characteristics in different evolution stages. There are a sedimentary Palaeo-high during Cambrian-Ordovician, a tectonic Palaeo-high during Silurian-Cretaceous and a buried Palaeo-high during Cenozoic. The Yakela faulted convex was formed by pre-Silurian tectonic events, and became the sedimentary material source during Silurian. Yingmaili anticline, Halahatang syncline, Akekule anticline, and Caohu syncline are formed in the early Hercynian accompanied by SN, EW, NW, NE-trending faults. A weak stretch and shear tectonism led to the re-activity of the pre-faults in Paleogene and a series of en echelon faults forms in the upper strata along pre-faults. The Eogene tectonism led to the Mesozoic tendency reverse. Buried after Cretaceous, the Shaya Uplift is located in the slope area of the Tarim Cenozoic basin. The Shaya Uplift structure controlled the accumulation and distribution of the oil and gas. Two oil and gas aceumutation zones formed along the Tiergen North-Yaha-Dayouertusi-Yangtake fault belts and Luntai-Yakela-Donghetang-Hongqi fault belts. In the south of the Shaya Uplift, it is a regional hydrocarbon accumulation area. There are deep and shallow oil and gas reservoirs in this area. The deep oil and gas reservoirs formed in the carbonate formations and secondary hydrocarbon reservoirs formed in the clastic rocks. The secondary hydrocarbon reservoirs are generally located above the large oil and gas reservoirs hosted in the carbonate. The oil and gas accumulation is controlled by the faults fractures, folds and unconformities. The dissolution difference of carbonate rocks led to the oil and gas reservoir complexity.