摘要
事件地层学是地层学的一个新的视角,通过对鄂尔多斯盆地南部晚三叠世长7,长6时期的浊流事件、火山作用事件及缺氧事件的研究与讨论认为,在盆地西南部及南部长6和长7油层组中的半深湖-深湖中发育的浊积岩具典型的浊流沉积特征,为湖相低密度流,并构成了该地区的主要储层类型;该时期发生了多期火山事件,这些火山作用事件与盆地有效烃源岩的形成休戚相关;缺氧事件主要发育于长7时期,属于地区性大型缺氧湖盆形成的缺氧事件。这些事件沉积的相互共同作用对延长组油藏的形成作出了巨大贡献:首先在长7时期,由于构造沉降、气候因素等因素影响,形成了深水环境,湖盆面积大,生物种类繁多,这为烃源岩提供了必要的物质基础;随着浊流事件、火山事件的发生,形成缺氧的环境,导致生物大量死亡埋藏,这些都为烃源岩的形成提供了有利的条件;长6—长7浊流沉积的浊积岩又是该地区的主要储层类型之一。正是这些事件沉积的相互共同作用,形成了该地区良好的油气藏。
The event stratigraphy is a new developing point to the stratigraphical geology. Discussion and investigation on turbidity currents, volcanic and anoxic event in the south Ordos Ba sin reveal that there have developed characteristic turbidite of lacustrine low density flow constituted the main reservoirs in semi-deep to deep lake of the Chang 6-Chang 7 oil-bearing in south Ordos Basin. Meanwhile, several volcanic events occurred which had close relationship with the formation of effective hydrocarbon source rocks. Anoxic events mostly developed in Chang 7 oil- bearing and belonged to the local large anoxia lake. It was thought that the interaction of these events made great contribution to hydrocarbon accumulation in the Yanchang Formation. Firstly, structural depression and climate complication during the Chang 7 stage resulted in large deep wa ter circumstance with numerous life-forms,which provided the material foundation for the formation of hydrocarbon source rock. Secondly, the subsequent occurrence of turbidity current and volcanic event led to anoxic circumstance. The death and burial of Ahundant living creature also provided favorable condition for the formation of hydrocarbon source rock. Therefore, it was the interaction between depositional and volcanic events that created the oil reservoir in south Ordos Basin.
出处
《矿物岩石》
CAS
CSCD
北大核心
2008年第3期90-95,共6页
Mineralogy and Petrology
基金
国家自然科学青年基金项目(编号:40602012)
四川省教育厅青年基金
油气藏地质及开发工程国家重点实验室开放基金
关键词
鄂尔多斯盆地
延长组
事件沉积
浊流
火山事件
缺氧事件
油气聚集关系
Ordos basin
Yanchang Formation
depositional event
turbidity current
volcanic e vent
anoxic events
hydrocarbon accumulation
