鄂北杭锦旗探区构造演化与油气关系

Relationship Between Tectonic Evolution and Hydrocarbon in Hangjinqi Block of North Ordos Basin

鄂北杭锦旗探区构造演化与油气关系研究比较匮乏,而该区构造演化对上古生界油气运聚的作用不容忽视。论文通过对研究区构造演化分析研究,结合前人成果,明确指出研究区先后经历了太古代-古元古代基底形成期、中、新元古代裂谷集中发育期、早古生代隆起剥蚀期、中晚石炭世-三叠纪的稳定克拉通发育期及中新生代的不均衡发育期等五个演化阶段。在研究区形成了早、中期的北西高南东低转变为现今的南西低北东高的构造格局。研究区构造演化与上古生界油气关系密切。具体表现为,古隆起及其演化控制了上古生界烃源岩的展布和演化,构造运动导致上古生界储层普遍致密化,基底形态及构造活动控制了区内构造圈闭的形成,构造演化控制了上古生界油气的运移和聚集,先后经历了中-晚侏罗世和早白垩世-至今两期油气运聚,油气运移方向分别以北向、北东向为主,在研究区南部斜坡发育根缘气藏,北部发育常规气藏。

Little research on relationship between tectonic evolution and hydrocarbon had been done in Hangjinqi block of northern ordos basin. In effect, tectonic evolution of studied area played an important role in upper Paleozoic hydrocarbon migration and accumulation. Based on former achievements, this paper focused on tectonic evolu- tion of studied area and pointed out definitely that this area experienced five phases of tectonic evolution, including Archean-Paleoproterozoic basement formation, Mesoproterozoic-Neoproterozoic rift centralized development, Early- Paleozoie uplift denudation, Middle-Late Carboniferous-Triassic hedreocraton development and Meso-Cenozoie dis- proportionate development. In this studied area, tectonic framework of higher in northwest in early metaphase changed into higher in northeast at present. Tectonic evolution made an important role in upper Palaeozoic reservoirs. Paleohigh and its evolution controlled distribution and evolution of upper Paleozoie source rocks. Tectonic movement made upper Paleozoic reservoir tight generally. Basement shape and tectonic movement controlled devel- opment of structural traps. Tectonic evolution controlled hydrocarbon migration and accumulation in upper Paleozo- ic. Studied area experienced two periods of hydrocarbon generation and expulsion in Middle-Late Jurassic and Early Cretaceous up to now. Hydrocarbon migrated mainly northward and northeastward, respectively. Slope part in southern studied area develops source-contacting gas, while northern one develops conventional gas.