现代曲流河沉积原型建模及构型级次特征探讨--以海拉尔河、潮白河为例

Prototype model of modern fluvial deposits and discussion on architectural units:a case study of Hailar River and Chaobai River

海上油田河流相储层非均质性强,构型表征是油藏精细描述的核心。基于前人研究,采用"将今论古"思路,针对海拉尔河、潮白河现代曲流河开展地质雷达探测,通过原型建模探讨了河流相储层构型级次特征,取得了以下认识:(1)由于沉积动力和主控因素的转变,河流相储层结构的建造过程以6级界面为过渡点,整体上,自低级次到高级次体现出由横向转为纵向的沉积趋势,6、7级构型界面是体系中的关键构型界面;(2)受古河谷地貌影响,河流沉积体内部表现出纵向多期叠置特征,是多期河谷阶地的体现,不同期次之间可发育相对连续稳定的层序界面;(3)单点坝多以残存体保存,由多个具有成因联系的残存单点坝组成的复合点坝体,横向一般以废弃河道为界,具有形成独立沉积体的条件,是曲流河砂体构型解剖中的重要构型单元。

Considering the great heterogeneity in fluvial reservoir of offshore oilfield？ Reservoir architecture charac-terization is the core for reservoir fine description. Based on previous study and under the research concept of his-torical comparison, this paper conducted GPR detection on modern sediments of meandering rivers, namely Haila.r River and Chaobai River. This paper, through prototype model reconstruction, reviewed and explored fluvial res-ervoir architectural units features, and concluded the following understandings： Firstly, due to the transformation of deposition dynamic mechanism and dominating factors, fluvial reservoir formation takes the 6th order interface as breaking point. As a whole, from lower order toward higher order, the sedimentation process of fluvial reservoir architecture tends to transfer from lateral to vertical, and the 6th and 7th orders are key interfaces. Secondly, under the influence of ancient valley landform, fluvial deposits present the characteristics of multi-stacked complex longitudi-nally, which is an indication of multi-stage valley terraces. Relati-vely continuous and stable sequence interfaces may be developed among different stages. Thirdly, individual point bars were mostly reserved in the form of remnant bodies. Generally, point bar complex, which is composed of several genetically related individual point bar remnants and takes abandoned channels as lateral boundary, may have favorable conditions to form isolated sedimentary units. Therefore, point bar complex is the most important unit for meandering ri-ver sand body architecture characterization.