UPPER OLIGOCENE-EARLY LOWER MIOCENE SEDIMENTARY FACIES AND RESERVOIR DISTRIBUTION PATTERN IN WENCHANG H ZONE IN THE WESTERN PEARL RIVER MOUTH BASIN

The Wenchang H zone was adjacent to the Shenhu uplift in the west of the Pearl River Mouth Basin. Tidal and fluvial processes were the main geological forces during early Oligocene to early Miocene that dominated and affected the deposition and distribution of the sand. In the Zhuhai Formation, owing to the influence of the activity of the Zhu Ⅲ south fault, the region received fan-deltaic deposits proximate to the Shenhu uplift. The activity of the fault and the diversity of the parent rocks controlled the advancing range of the point sediment sources and the distribution pattern of the delta-fan. Moreover, the front of the fan suffered from the alternation of destruction and reconstruction may keep both the characteristics of river and tide. In the Zhujiang Formation, with the gradually rising of the sea level, there developed flooding tidal deltas in the relatively restricted barrier bar-lagoon system. Tidal passages were located at the lowland area on the middle northern Shenhu uplift. Because of the scouring of the current moving back and forth, multi-period of superimposition of tidal sand-bars is observed. For study of the distribution of the linear sand-bars, micro-palaeogeomorphology research in combination with integrated well-seismic data interpretation is recommended.