中国西北地区石油天然气地质基本特征

FUNDAMENTAL CHARACTERISTICS OF PETROLEUM GEOLOGY IN NW CHINA

中国西北地区是以若干克拉通为基础，通过造山带拼合形成的盆地山脉省。主要盆地都具有古生界台盆相、中生界泛盆地相与新生界磨拉石相三层结构；历史发展经历了三期拉张，四期挤压，相应产生了海相、海陆交互相与陆相三大套生储油岩系，并出现四次生烃与成藏高峰；海相与陆相两套层系都有丰富的油气资源，但石油地质特征不同，应施于不同的研究与勘探对策；发育三类盆地，以克拉通和前陆盆地找油气潜力最大。

The basic tectonic framework of NW China is an assemblage of several cratonic blocks pieced together with orogenic belts. Most of the major sedimentary basins occurring in the region developed three-layered architecture characterized by Paleozoic marine sequence, Mesozoic non-marine sequence and Cenozoic molasse facies. During the evolutional process,three extensional periods and four compressional phases alternately appeared in the region and three suites of soure rock, reservoir and caprock assemblage were therefore formed in some successive basins. The study made by the authors shows that the region underwent four main periods of hydrocarbon generation and pools formation due to the coincidence of hydrocarbon generation processes of different source beds superimposed on each other and the several tectonic compressions happening in coincidence with or a bit later than the hydrocarbon generations,dominantly in the end of Early Paleozoic ,Permian and Late Jurassic to Cretaceous as well as Late Tertiary. The petroleum exploration done in the region in the past decades indicates that the two suites of marine and nonmarine sequences have rich oil/gas resources,but different exploratory countermeasures should be taken into practice owing to their different characteristics of petroleum geology. Three types of sedimentary basins are classified and the craton and foreland basins have been verified to be the largest potentialities of petroleum resources for the further exploration.