226 / 2019-06-28 09:52:17

Fine characterization of meandering fluvial deposit based on multi-scale fusion of core, wireline log, seismic data, and modern river, a study on the Gudong oilfield, Zhanhua Sag, Bohai Bay Basin, Chi

Meandering river,Core,Wireline log,Seismic data,Mapping methods

Most of China's oil-bearing basins are mainly composed of continental clastic rocks. 92% of the proven and invested oil and gas reserves occur in the terrigenous clastic reservoirs, of which the fluvial and delta facies are the main carriers of petroleum resources, accounting for 42.6% and 30% of the developed reserves, respectively. The fluvial facies reservoir has the characteristics of fast phase change in the plane and heterogeneity in the vertical direction. In order to finely characterize the architecture of the fluvial deposit, the study based on core, logging, and seismic synthesis can finely characterize the fluvial deposit from different scales. Under the guidance of the lateral migration mode of the meandering river, through the genesis-structure analysis, combined with the shape of the modern meandering river, completes the mapping of the section and plane phase diagram of the meandering river.
Based on the core data of sealed coring wells, the logging characteristics of different microfacies are clarified by log response characteristics, and different microfacies logging phase templates are established to build the foundation for the identification of non-coring microfacies. Through the combination of well and seismic data, the continuity of the sand body is analyzed and the stratigraphic correlation of the small layer is guided. The sand body distribution is also combined with the seismic slices. The plane-section interaction method is used to complete the sedimentary microfacies of the meandering river. In the process of drawing the well section profile and the plan of the sedimentary microfacies, the lateral migration model of the meandering river is fully referred to. The thickness of the sand body is different at different locations in the meandering channel. Therefore, when drawing the phase profiles of the correlation well, the position of the well passing through the fluvial channel should be referred to, which can avoid the disadvantages of consistent sand body shape when drawing the well profile. When drawing the plane phase diagram, the plane phase diagram conforms to river dynamics and the evolution of meandering river migration under a reference to the log response shape, meandering river mode, and modern river geomorphology with the dense well-net constraints. In the process of analyzing the lateral migration of the meandering river, it is necessary to identify the interlayers of the point bar. Based on the observation the lateral mode of the modern river and the ancient river point bar, the upstream point bar is often eroded by the water, and the downstream point bar is relatively well preserved. Combined with the Gudong meandering river, the migration mode of the point bar was further explored, which makes the architecture study of the meandering river more reasonable.