Abstract: Based on core and logging data analysis, Q4 member of Cretaceous in Fuyu Oilfield, Jilin province is recognized to be a set of shallow water delta deposition according to its depositional setting, material sources orientation, sedimentary characteristics and sedimentary structure. With a deposition of shallow water delta front as its main body, it is mainly composed of five sedimentary microfacies, such as underwater distributary channel, underwater interdistributary area, underwater natural levee, underwater crevasse splay and arenaceous shallows. In addition, the planar distribution law of sedimentary microfaices including 4 oil layer groups and 13 layers of Q4 member of Cretaceous are studied on the basis of microfacies analysis of individual well from integration with large quantities of geophysical logging and log data. The results show that this study area is located at the front of the delta front while in lack of mouth bar that was existing in previous literatures. And most underwater distributary channel, developing in the 5, 6, 8 and 10 layers, distribute in the direction of NNE and SN in bands. The shifting of channel center in terms of the main channel shifting has resulted in unsteady distribution of channel sand bodies in plane. The detailed research of microfacies has guided a direction for potential tapping of remaining oil in main productive layers and future development.

Key words: Fuyu Oilfield, Q4 member, sedimentary microfacies, shallow water delta, layer