Abstract: The Feixianguan Formation in the Paleo-Central Depression of the Northern Sichuan Basin hosts high-yield quality natural gas reservoirs in the dolomitized oolitic limestone under the control of sedimentary facies. Understanding the sedimentary characteristics and distribution patterns of the oolitic limestone could help guide the exploration and development of natural gas in this area. Specific sedimentary facies zones of the Feixianguan Formation were distinguished using rock core from Well Q1 in the study area via microscopic thin-section observation. Results indicate that the study area contains 6 types of ooids, mainly surface ooids and calcitic-metacrystic ooids, followed by true ooids, “negative ooids” (or hollow ooids due to selective dissolution after oolite formation), dolomitic-metacrystic ooids, and some complex ooids. Various types of ooids were mixed and deposited at different depths, enriched in mainly micritic-oolitic limestone, micritic dolomictic-oolitic limestone, and oolitic sparite. The analysis on the occurrence and microscopic characteristics of ooids suggested that the ooids were deposited in a platform environment with barrier coasts, and their sedimentary microfacies include 6 types: ooid beach, oolitic biological reef, tidal channel, bioclastic beach, lagoon ooze, and stagnant water ooze. Ooids were found in 3 types of microfacies: ooid beach, oolitic biological reef, and tidal channel. Classification of sedimentary facies showed that metacrystic ooids were deposited near wave base in open platform, and enriched mostly in micritic dolomictic-oolitic limestone. The oolitic sparite contains all types of ooids, while the micritic dolomictic-oolitic limestone contains only calcitic-metacrystic oolites and “negative oolites”, indicating tidal channel microfacies and restricted platform facies. The metacrystic ooids in the dolomictic-oolitic limestone are characteristic of dolomitic metacrysts, representing open platform facies. The establishment of sedimentary facies is beneficial for paleogeographic reconstruction of the study area, thereby determining the location of quality productive reservoirs, and providing reliable basis for logging data interpretation and evaluation for effective oil and gas extraction.