Abstract:

The composite seismic wave of the reflection horizon T5 includes three positive and two negative highamplitude events. The middle positive one is the seismic event of T5 interpreted in this study; it is the best stratigraphic correlation marker and seismic interpretation horizon because of its stability, continuity, and extensive distribution;it is a surface of downlap termination in the deepsag area and a surface of onlap termination in the alongshore and highlandform area. Corresponding to T5, the middle stratum is composed of limestone, and limestone interbedded with sandstone or mudstone; and it is only composed of sandy mudstone in the northwest of Lufeng Sag. It was formed in the first transgression stage of sedimentation during the transition of the Lufeng Sag from a shore zone to a neritic shelf under the long transgression background after the Nanhai movement, with the age of 185 Ma and formed around the maximum flood stage of thirdorder sequence TB21. Above the middle stratum, a set of sandstone strata lies locally, formed as the falling system tract of TB21 and another stage of transgression sedimentation. Under the middle stratum, an interbedded stratum of sandstone and mudstone lies as a fourthorder sequence of TB21. Assemblages of petroleum reservoir and seal rock developed in and about the reflection horizon T5, which was controlled mainly by the sequence cyclicity and successive landform.

Key words:

Key words: Lufeng; T5; seismic reflection; sequence; petroleum; exploration