南襄盆地襄枣坳陷深层海相古生界含油气前景初探

THE STUDY OF PETROLEUM-BEARING PROSPECT OF MARINE PALEOZOIC OF THE XIANG-ZAO DEPRESSION IN THE NANXIANG BASIN

南襄盆地襄枣坳陷主要为受襄樊—广济断裂控制的南断北超的中新生代箕状坳陷,但中新生界经多年勘探未获突破。通过"造山带北侧油气资源战略选区"课题的调查研究,发现襄枣坳陷周缘及深部分布大片未变质的海相古生界。其中,下寒武统底部含磷泥页岩是潜在的优质烃源岩;下古生界白云岩及内部岩溶侵蚀面形成较好储集空间;下古生界含膏白云岩是潜在的盖层,具备形成油气的基本地质条件,但热演化程度偏高。襄枣坳陷深部海相古生界油气是值得深入探索的新层系和新领域。

The Xiang--Zao Depression of the Nanxiang Basin is a half graben-like sag in Mesozoic--Cenozoic with faulted in the south part and overlapped in the north, which is mainly Controlled by the Xiangfan--Guangji fault, and has not been a breakthrough through many years of exploration in the Mesozoic--Cenozoic. Through the ＂petroleum sources of strategic electoral districts on the northern edge of the Qinling--Dabie Orogenic Belt＂ subject research, found that nonmetamorphose rock of Paleozoic marine strata was distributed in the periphery of Xiang--Zao Depression and its deep part. Among which, mudstone--shale containing phosphor is a potential high-quality source rocks at the bottom part of the Lower Cambrian; Dolomite and internal erosion surface formation are better reservoir strata in the Lower Paleozoic; Lower Paleozoic Dolomite containing paste is potential covered layer, which forms the basic geological conditions of oil--gas . But the source rocks are having high degree of thermal evolu- tion. Paleozoic oil--gas of deep marine strata in the Xiang-Zao Depression is the new layer system and a new field, which is worth in-depth exploration.