Study On Fine Oil Layer Correlation Of Oil-bearing Formations, North Wuerxun Depression

Wuerxun Depression is located in the south of Hailaer Basin. The study area, Wubei Depression, is controlled by the Wuxi fault system and on the east of Wubei Depression is Wudong slope structural belt. The research area is mainly composed of both forward and negative tectonic units whose direction is latitudinal. From north to south they are Huang Qimiao anticline structural belt, Zha Hemiao sag, Surennuoer strike-slip fault belt, Wubei sag and Wudong slope structural belt.Based on the information of core, well logging and seismic data, guided by the theory of Sedimentology, Sequence Stratigraphy and Seismic Stratigraphy, we analyzed the tectonic characteristics and sedimentary evolution of the basin. And controlled by the dense regional sections which involves both well and seismic information, we can recognize the sequence boundary and flooding surface, build isochronous third-order sequence framework in the study area. Based on these work, we recognized that the boundary between Damoguaihe Formation and Nantun Formation should change from the previous research. According to the paper, the oil-bearing formation located in the upper Nantun Formation, Lower Cretaceous, cross over two third-order sequences. The main part of oil-bearing formation is in the bottom of Damoguaihe Formation rather than in the upper Nantun Formation. The main genetic type of the reservoir is the slumping turbidite sedimentation which locates in the LST of Damoguaihel Member; the genetic type of the lower reservoir is delta front and sand sheet which is located in the HST of upper Nantun Formation. Based on the genetic type of the reservoir and tectonic characteristic in the study area, we can predict that the reservoir type in Wubei Depression can be classified as tectonic-lithologic deposit.Restricted by the third-order sequence framework, guided by the theory of base level change, we can analyze the dynamic response to the stratigraphy and sedimentology which is caused by the change of A/S. Next, we can divide the forth-order sequences (oil layers) and make correlation and make correlation in the oil-bearing formations. We analyzed the characteristics of the distribution of the oil layers in the Wubei Depression. Especially for the main production zone, S131zone and S102 zone, we made correlation between these two zones and analyzed the change of the thickness.In the rifted basin, macroscopic characteristics of palaeotectonic and palaeogeomorphology are important factors which control the sequence configuration, sequence thickness and distribution of the sedimentary system. Secondary geomorphology and microtopography in the rift control the distribution of the sedimentary facies and reservoir. In this paper, we use the technique of palaeogeomorphology reconstruction to analyse the residual thickness, denuded thickness and the characteristics of the palaeogeomorphology in the period of every oil layer, which can be used to predict the distribution of the oil layers.