The Chang-6 member of the Yanchang Formation in the Jing'an oilfield is studied to understand its sedimentary facies. By analyzing core data from wells and profiles, researchers identified it as a lacustrine delta system dominated by delta front sub-facies. They found that depositional microfacies like channel mouth bars and underwater distributary channels are important for forming large-scale reservoirs. These areas should be targeted for further petroleum exploration.