扶新隆起带南部扶余油层高分辨率层序地层分析

依据岩心、录井和测井资料,对松辽盆地扶新隆起带南部扶余油层各级次基准面旋回演化规律及高分辨率层序地层模式进行研究。结果表明:扶余油层发育1个长期基准面旋回的上升半旋回、4个中期基准面旋回和13个短期基准面旋回,地层厚度受继承性古隆起控制向盆地阶梯状减薄;基准面的发育过程经历早期的缓慢上升阶段、中期的快速上升阶段、中后期的缓慢上升阶段及末期的快速上升后略有下降阶段,依次发育高能和低能河控三角洲平原、近岸沉积区、三角洲前缘-前三角洲;扶余油层底部为长期基准面下降至上升转换面,A/S值远小于1,砂体几何形态以多层式为主;随着基准面上升,A/S增加,原始地貌要素保存程度的增强导致河道沉积以侧向加积为主,砂体以孤立式为特征;向上变深的非对称型中期基准面上升半旋回早期主要发育厚层分流河道沉积,构成扶余油层的主要储集砂体。

Analysis of high-resolution sequence stratigraphy of Fuyu oil layer in the southern Fuxin Uplift

Based on cores, log and well-log data, evolution of all levels base-level cycles and high-resolution sequence stratigraphic model were analyzed in Fuyu oil layer of the southern Fuxin Uplift. The results show that one long-term, four middle-term and thirteen short-term base-level cycles were classified. Strata thickness is controlled by the inherited palaeo-uplift and it appears stepped thinning toward the basin. Base-level mainly experienced four stages: the early rising slowly stage, the middle rising quickly stage, the middle and later rising slowly stage, the end rising quickly and falling slightly stage. Fuyu oil layer has developed into high-energy fluvial-dominated delta plain, low-energy fluvial-dominated delta plain, coastal deposition area of fluvial-dominated delta plain and delta front to pro-delta deposition during those four stages. The bottom of Fuyu oil layer is a turnaround surface of long term base-level falling to base-level rise. Its A/S is far less than 1. The geometry of sandbody is maily multi-layered. With the base level rising, A/S and the preservation degree of original landscape elements increase gradually. This is the reason why channel deposit is mainly lateral accretion, and the sandbody is isolated. The early rising hemicycle of non-symmetry middle-term base-level cycle deepening upward mainly forms thick distributary channels, which constitutes the main reservoir sandbodies of Fuyu oil layer.