Research On Sandbody Distribution And Sedimentary Model In Shallow Lacustrine Fluvial-dominated Delta Front

It is increasingly difficult to find the residual oil in the east of Xing Six area of daqing oilfield.However,the water flooding characteristics and residual oil characteristics reflected in the core of coring well still have some potential for excavation.Therefore,it is particularly important to conduct fine anatomy of the subfacies reservoir and to clarify the sedimentary pattern and distribution characteristics of the sand body in the delta front.In this paper,on the basis of the dense well pattern in the study area,using the data of logging,coring Wells and other geological cores of S?reservoir group study.The S? reservoir belongs to the secondary and tertiary period of yaojia formation.Firstly,the fine division and comparison of sand body level in the S reservoir group were carried out,and the stratigraphic framework of 29 time units in the whole region was established.By analyzing sedimentary background and single well sedimentary microfacies of coring well,1 phase,1 subphase and 7 microfacies of the study area were clarified,and the logging microfacies model was established by combining the electrical test characteristics.Then,the microfacies of the planar sedimentary microfacies were carefully identified by each well,and 29 sheets of sedimentary microfacies were drawn,and then the evolution law of sedimentary environment was analyzed.Based on the energy intensity of the river,the supply degree of the source and the three main controlling factors of the energy intensity of the lake wave,three sedimentary models of the delta front subfacies were established: The sedimentary sequence of the "river control" sedimentary pattern in the inner leading edge is controlled by the underwater distributary channel and is shown by the belt.The sedimentary sequence of the "river and lake wave dual-control" sedimentary mode of the inner and outer leading edge is controlled by the underwater distributary channel and the lake wave.The "wave control" sedimentation pattern is controlled by the lake wave,and the sedimentary sequence is banded or concentric annular.Based on the study of sedimentary microfacies,the authors identified five types of sand bodies in the study area and four types of single sand bodies,and analyzed the surface and vertical distribution characteristics of sand bodies.Finally,through the above research,the spatial distribution pattern of two types of sand bodies was summarized based on the supply degree of material source and the elevation of lake plane: the spatial distribution pattern of sand body in progradation,the spatial distribution pattern of the deposited sand body.