The Study Of The Subsidence,Uplift, Erosion,Hydrocarbon-generating, And Hydrocarbon-bearing Of The Source Rocks In The Upper Paleozoic Of Ordos Basin

The Study of the Subsidence,Uplift, Erosion, Hydrocarbon-generating, and Hydrocarbon-bearing of the Source Rocks in the Upper Paleozoic of Ordos Basin is key to the study of Unconventional and conventional oil and gas accumulation and distribution uniformity correlation in the area, Previous studies comparing its weak. This paper makes full use of existing core, cast thin section, fluorescence thin section, gas logging, logging, analysis assay data. Based on the previous analysis, the research idea is combining the basin sedimentary, subsidence geological analysis and geochemical testing. At the analysis of the structural, sedimentary facies and organic geochemistry, this paper preliminarily studied the differences of upper Paleozoic main source rock in subsidence and uplift, the hydrocarbon generation and hydrocarbon bearing of source rocks, and their relationship, made the following understanding:(1) In the late early Cretaceous, the biggest range of subsidence of the main source rocks in the upper paleozoic erathem of the Ordos Basin is located in the area of Zhidan-Wuqi, the sedimentary thickness reached4500m. At the same time, a slightly smaller sunken appeared in the northwest of the basin along the area of Tianchi-Yanchi,the sedimentary thickness reached4300m. The sedimentary thickness became smaller gradually from the area of Zhidan-Wuqi which was the center to the edge of basin and the smallest range of sedimentation appeared in the northeast of the basin along the County of Jungar, which was1900m in depth. Since the Late Cretaceous, The whole basin uplift and denudation in the area of Iron Aksu and Huanxian-Zhenyuan is the most weak, the denudation thickness is about200-400m, the eastern denudation thickness is greater than the Western, the denudation thickness is up to1800m in the area of Yonghe-Yichuan-Jixian. The settlement center of the upper Palaeozoic source rocks in Erdos basin in the area of Jiyuan-Majiashan-Shancheng, the sedimentary thickness is4200m, he sedimentary thickness is1800m in Edge of the basin.(2)The sedimentary thickness of coal bed and dark shale in upper paleozoic erathem of the Ordos Basin is large, which can reach30meters and130meters respectively. Coal organic carbon content is higher, the average TOC of Shanxi Formation is67.34%, Taiyuan Formation80.7%, upper Paleozoic erathem3.58%. All coal organic matter is type Ⅲ, while dark shale is type Ⅱ and few type Ⅰ. The Ro subject is between1-2%, and most of the them are in mature and high mature stage.(3)The of source rock under a fluorescence microscope in the Upper Paleozoic of the Ordos Basin, the color is green. And in pores or cracks of flakes, light intensity, hydrocarbon bearing good. The average S1of coal is67,34%, the average Si of dark shale is67.34%dark shale. Hydrocarbon-bearing characteristics of the Upper Paleozoic source rocks can be divided into threes, one type is high value area of the total hydrocarbon gas is located in the shale and coal, one type is high value area of the total hydrocarbon gas is located in the interface of sand and and, the another type is high value area of the total hydrocarbon gas is located in the shale mezzanine.(4) In buried within the scope of the Upper Paleozoic main source rocks in Ordos Basin,it is Between1800-4200m, hydrocarbon source rock maturity is generally greater than0.9%, and generally hydrocarbon.