华北加里东侵蚀面与油气富集

ON THE CALEDONIAN EROSION SURFACE AND THE ACCUMULATION OF OIL/GAS IN THE AREAS OF THE NORTH CHINA

陈光汉

Chen Guanghan

地质矿产部华北石油地质局 郑州 450006

North China Bureau of Petroleum Geology, MGMR

本文叙述华北地区加里东侵蚀面即奥陶纪海相碳酸盐岩顶面(Tg波组)的划分和对海相碳酸盐岩油气藏形成的控制。此面沉积间断时间长达1.3亿年,缺失志留、泥盆系和下石炭统,侵蚀面上下地层为平行不整合接触。由于长期裸露地表,遭受风化、淋滤、溶蚀、剥蚀,奥陶纪碳酸盐岩的溶孔(洞)、溶缝甚为发育,是极好的油气储集岩。华北地区古生界碳酸盐岩大油气藏的油气源岩,除其自身外,下第三系更是重要的油气源岩。油气生成后,通过断裂、不整合面等通道,聚集在加里东侵蚀面上下的圈闭中,形成高产油气藏。

The author describes the characteristics of the Caledonian erosional surface in the North China, i. e the top surface of the Ordovician marine carbonate system (Tg reflection wave group), and its controlling over the formation of the oil/gas pools in the marine carbonate sequences. The sedimentation hiatus for such an erosional surface lasted as long as 130Ma with the ommission of the Silurian,Devonian and the lower Carboniferous systems. The stratigraphic contact along the surface is an unconformity. Since the prolonged erosions with weathering, leaching,dissolution and denudation, the dissoluted pores,caves and fissures have been well developed in the Ordovician carbonate sequences, thus they can be excellent reservoir rocks for oil/gas accumulations. However, the Tertiary sequences are of most significant source rocks for large oil/gas pools in the Paleozoic carbonate reservoir, except for the source rocks of the carbonate rocks themselves. Through the faults and the uncomfornities, the generated hydrocarbons would accumulate and migrate into the traps located above or beneath the Caledonian erosional surface and prolific oil/gas pools would be developed.

https://doi.org/10.11781/sysydz199201046