鄂尔多斯盆地林镇地区延长组长2沉积微相与油气分布

Characteristics of the Sedimentary Microfacies and the Oil and Gas Distribution of Chang 2 Reservoir of Yanchang Formation in Linzhen Area,Ordos Basin

鄂尔多斯盆地林镇地区处于伊陕斜坡西南部,在长2沉积期研究区内发育辫状河三角洲前缘亚相沉积,沉积微相主要为水下分流河道、水下分流河道间、河口坝和远砂坝,物源主要来自北东和南西两个方向。林镇地区长2油藏的分布与沉积相关系密切,油藏主要分布于水下分流河道末端和河口坝的混合区,以及水下分流河道的侧缘,另外在远砂坝区也有少量油藏分布。区内长2期的辫状河三角洲前缘亚相沉积环境控制了长2储集层岩性的横向变化,同时区内长2地层普遍发育低幅度鼻状构造隆起,因此在构造圈闭条件和岩性圈闭条件共同作用下形成构造─岩性复合油藏。

Linzhen area is situated in the southwestern Yi-shan slope of the Ordos Basin with the braided river delta front subfacies at Chang 2 Formation. The front subfacies of braided river delta of this area can be further divided into four types of sedimentary microfacies. Underwater braided distributary channel, un- derwater distributary interchannel, river-mouth bar and distal bar. And the provenance mainly comes from northeast and southwest directions. Chang 2 reservoir of Linzhen area has close relationship with deposi- tional facies. The joint zone of river-mouth bar, the end of underwater distributary-channel, and the lateral distributary channel, are the distribution of reservoirs. Meanwhile, .there are few reservoies in the area of distal bar. Owning to the lithology of reservoir bed in Chang 2 reservoir lateral changes in control of the sedimentary environment of the braided river delta front, and nose structure uplifts general development in the strata of chang 2 reservoir, the structural-lithologic traps were formed in the interaction of the struc- tural traps and the lithologic traps.