华北典型箕状断陷盆地层序地层学模式及其与油气赋存关系

SEQUENCE STRATIGRAPHIC MODELS AND THEIR RELATIONSHIP TO OIL AND GAS OCCURRENCE IN TYPICAL FAULTED BASINS, NORTHERN CHINA

本文根据层序地层学的基本原理,立足东部箕状断陷盆地的特点,以冀中拗陷和二连盆地为重点研究对象,提炼出陆相断陷盆地层序地层学模式,在缓坡带,以风暴浪基面作为“陆架边角”的参照物,层序地层特征相似于海相被动大陆边缘背景;在陡坡带则截然不同,并以湖面与边界断裂的交点取代“陆架边角”,各体系域所含沉积体系与海相模式不尽相同,在盆地形成初期的层序,低水位体系域发育,湖泊消亡以后,主要发育高水位体系域。此外,本文还探索了层序地层与油气赋存的关系,指出富砂的“盆底扇”是今后勘探开发的重要方向。

The sequence stratigraphic models of nonmarine sediments deposited in faulted basins are given according to the basic concepts of sequence stratigraphy and the characteristic of faulted basins located along the east coast,such as Jizhong Depression and Erlian Basin. In these models, the characteristic of sequence stratigraphy of the gentle slope, where the storm base can be regarded as the reference for the "shelf edge", is similar to that of the passive continental margin,but on the steep slope,where the "shelf break" is the intersected point at which the lake level crosses the steep slope,the characteristic is different from that of the passive continental margin. And the depositional system tract of these models include some depositional system different from that of marine model; the sequence deposited in the early stage of the basin is mainly composed of lowstand systems tract, and when the lake was withered,only highstand systems tract consisting of fluvial and alluvial systems develop. In addition, The paper discusses the relation of the sequence stratigraphy to the oil and gas occurrence,and points out that the sand-prone lake-floor fan is the favorable region for the exploration and production of oil and gas.