万安盆地位于我国南海西南端、印支半岛的东南海域，它是一个新生代走滑－拉张盆地，沉积了逾万米厚的地层。根据地震、钻井资料分析，把万安盆地新生代地层自上而下划分为第四系、广雅组、昆仑组、李准组、万安组及西卫群和人骏群，探讨了各组、群的时代属性和特征，认为它们分别对应于第四纪、上新世、晚中新世、中中新世、早中新世及渐新世—晚始新世和早、中始新世，缺失古新世地层，同时认为西卫群和万安组是万安盆地的主力烃源岩层。 Wan’an Basin is located in the southwestern end of the South China Sea in China, the southeastern waters of Indochina Peninsula, it is a Cenozoic slip-stretching basin, deposition of more than ten thousand meters thick strata. According to the analysis of seismic and drilling data, the Cenozoic strata in Wan’an Basin are divided into Quaternary, Guangya, Kunlun, Lizhun, Wanan and West Wei and Renjun groups from top to bottom Group and group, they are respectively corresponding to Quaternary, Pliocene, Late Miocene, Middle Miocene, Early Miocene and Oligocene - Late Eocene and early, middle Late Pliocene, missing the Paleozoic strata, at the same time that the West Wei and Wan’an Formation is the main source rocks in the Wan’an Basin.