Sedimentary charactersitics and distribution regularity of oolitic beach reservoirs in Feixianguan formation in Tieshan—Huang Nitang area of Northeast Sichuan Basin

By comprehensively using drilling, logging, coring and regional structure material analysis, the sedimentary characteristics of oolitic beach reservoirs in Feixianguan formation in Tieshan-Huang Nitang area have been carefully studied. The results indicate Kaijiang-Liangping trough with northwest direction gradually developed in the late Permian performs the control function on the distribution of the oolitic beach. At the same time, the relative uplift or depression developed by basement fracture with northeast direction through cutting also has an effect on the distribution of the oolitic beach. In combination with global sea level changes, it is believed that during late Permian there was a larger regressive at the end of Changxing period, and the oolitic beach was mainly developed in the mid-late period of regressive. At the early stage of Feixianguan period, because of platform groove differentiation sedimentary pattern, Platform margin oolite beach was mainly developed. Up to the Feisan period, as the trough was basically filled, the oolite beach inside platform was only developed in submarine microrelief highlands. As the trough was completely filled up, the particle beach was no longer developed and the research area gradually evolved into regional tidal-flat facies.