鄂尔多斯盆地延长组3种沉积物重力流及其含油气性

依据大量岩心、露头观察与分析测试资料,在鄂尔多斯盆地湖盆中心深水区延长组长6段识别出3种类型的沉积物重力流,即砂质碎屑流、经典浊积岩和滑塌岩,其中砂质碎屑流是在我国陆相含油气盆地中新发现的一种砂体成因类型,属于层流;而经典浊积岩由浊流作用形成,属于紊流;滑塌岩则是在深水环境中由于滑动、滑塌作用形成的滑塌变形体。三者在流变学特征上存在本质差别,以往延长组深水沉积研究夸大了浊流的沉积作用。从时空分布看,三者在空间上相互依存,在时间上相互转化;从含油气性看,砂质碎屑流最好,经典浊积岩A段次之,而滑塌岩较差。进一步研究认为,砂质碎屑流为湖盆中心地区油井产量的主力贡献者,其平面分布控制着油气藏的富集与高产。

Three types of sediment gravity flows and their petroliferous features of Yanchang Formation in Ordos Basin

Based on cores,outcrop observation and analysis test data,three types of sediment gravity flows are identified in the sixth memberof Yanchang Formation in the deep waterarea of lake centerin Ordos Basin,including sandy debris flow,classic turbidity current and slump.Sandy debris flow is a new-discovered sandy in the continental petroliferous basin and comes under laminar flow,turbidite formed by turbidity current is turbulent flow,and slump are slumping deformable bodies caused by sliding or slumping in the deep water environment.These three types of gravity flows have essential distinction in the rheological features.In the past,the deposition of turbulent flow was dominant in the research of deep water sedimentation in Yanchang Formation.Three of them are attached in space and transformed in time.From sandy debris flow to slump,the petroliferous property is weakened,and the A section of classic turbidity is moderate.The further study shows that sandy debris flow is the main contributor for the production in the deep water area of lake center,and its plane distribution controls the accumulation and high production of the reservoir.