Abstract: Fan delta is the important reservoir, and its reservoir quality variations strongly influence the distribution of residual oil. It was previously believed that the physical property rhythm and particle size rhythm of sandstone reservoirs were consistent. But it was not clear whether the physical property rhythm and particle size rhythm were consistent for fan delta glutenite reservoirs with coarse grain size. Field survey, unmanned aerial observation and indoor experiments were used to investigate the fan delta of Sangyuan outcrop within Xiguayuan Formation of Lower Cretaceous in Luanping Basin, aiming to analyze the quality variations and control mechanism. The results show that: the small conglomerates and coarse sandstones with moderate sorting and low argillaceous content have the higher original pores and more compaction-resistant, and have the best physical properties; when granularity becomes coarse with worse sorting, and the argillaceous content increases with the granularity finer, the physical properties of the reservoir become worse. In the positive rhythmic distributary channel and the positive rhythm mouth bar, the vertical upward as the medium-fine conglomerate becomes to the medium-fine sandstone, reservoir physical properties from the bottom to the top become better to worse, and as the lateral granularity from the middle to sides becomes finer, the physical properties of the reservoir become worse. The anti-rhythm mouth bar from the bottom to the top becomes from fine sandstone to coarse sandstone and small conglomerate, the physical properties become better, and as the lateral granularity from the middle to sides becomes finer, the physical properties of the reservoir become worse.

Key words: Luanping Basin, Xiguayuan Formation, fan delta, Sangyuan Outcrop, reservoir quality variation