Analysis of Sedimentary Facies of the Fuyu Formation in Y Oilfield

This paper takes the Furuyi oil layer of Daqing Y Oilfield as the research object. By combining core observation, experimental analysis and logging data, the deposition facies characteristics of the oil zone are systematically analyzed. The study shows that the Furuyi oil layer is located in the Changyuan structural belt of the central depression area of the Songliao Basin and belongs to the fourth section of the Quantou Formation of the Lower Cretaceous. It was formed in the early stage of the depression's river-reef sedimentary environment. The source area was from the northern Nehe River-Baiquan and the western Baicheng-Baoqiang regions. The formation thickness is 150-250 meters. Sandstone and mudstone interbeds form the primary component of the rock composition. The production, storage and cover combination is good. The Furuyi oil layer mainly develops meandering river facies (including river channels, river floodplain subfacies and multiple microfacies) and delta facies (including plain, front subfacies and multiple microfacies). The rock types, sedimentary structures and logging response characteristics of each facies type are significant. Vertically, the oil layer shows a multi-cycle positive cycle structure, transitioning from meandering river facies to delta facies from bottom to top; horizontally, meandering river facies are distributed in the northern and western source areas, and delta facies are located in the central and southern areas. The sand bodies are distributed in strips or lenses along the source area, and the microfacies of beach and river mouth dam have the best reservoir performance. The study has clarified the sedimentary facies and sand body distribution patterns of this oil layer, providing geological basis for oil and gas exploration and development.