Abstract: The Enping Formation is the main source rock that has been proven in deep water area of the Baiyun sag, the Pearl River Mouth Basin. Understanding its sedimentary evolution and key controlling factors is essential for oil and gas exploration in the Baiyun sag. Through comprehensive analysis of wells, cores, seismic data and palaeo-biology, it is believed that the "source to sink" system apparently varied during different sedimentary stages of the Enping Formation. During the early-middle sedimentation stage, the main provenances were the Mesozoic igneous rocks in the uplift areas around the Baiyun sag. during the late sedimentary stage, the source materials were carried by the ancient Pearl River into the Baiyun sag from the South China fold belt as the principal migration pathways in the north of the sag were gradually opened. Correspondingly, proximal small braided delta, fan delta and beach bar dominated by paleo-troughs were deposited in the Baiyun sag during the early-middle sedimentation stage of the Enping Formation, and large continuously-transgressive coal delta was deposited during the late sedimentation stage. The variation of "source to sink" system dominated the plane distribution of the Enping Formation near-shore coal measure, far-shore terrestrial marine and closed bay marine source rocks, and controlled the dispersed distribution of coal-measure source rocks during the early-middle stage and the vertical diversity of extensive development during the late stage. Moreover, the variation of "source to sink" system allowed for the development of lithologic-stratigraphic targets that were mainly derived from proximal fan delta, braided channel complex and beach bar during the early-middle sedimentation stage, and the lithologic-stratigraphic targets dominated by delta-front transgressive complex sand bodies during the late stage.

Key words: source rock, sedimentary environment, lithologic-stratigraphic reservoir, Enping Formation, Pearl River Mouth Basin, Baiyun sag