Research On Sequence Stratigraphy Of Huaguang Depression In The Qiongdongnan Basin

Based on the theory of sequence stratigraphy and sedimentology, using lots of two-dimensional seismic data and three-dimensional seismic data, the sequence stratigraphy of Huaguang depression in the Qiongdongnan basin is analysed, and the framework of sequence is built. And then using of high-quality 3-D seismic data of Huaguang depression, the high precision sequence stratigraphy is studied, and characteristics and evolution of sedimentary faces of the study area is analysed, the sequence stratigraphic model of the key formations on Huaguang depression is concluded. In the end, the typical types and distribution of favorable sand is pointed out.Since the Cenozoic, Huaguang depression has experienced the sedimentary evolution which is from the lake or bay-phase in the faulted period, to the littoral-neritic facies in the thermal subsidence period and to the typical shelf-slope facies in the period of intense depression, and developed a series of typical facies and their subfacies, such as the nearshore subaqueous fan, delta, shore-tidal flat and biological reef. The sequence internal structure of Lingshui Formation, Sanya Formation and Meishan Formation in 3-D area of Huaguang Sag has two kinds of devolopemental patterns, which is trassgressive + high systems tract and low +trassgressive systems tract.The typical sand types in Huaguang Depression include the nearshore subaqueous fan, fan-delta and biological reef.And favorable sands include the fan-delta sandstone, shore sandstone and nearshore subaqueous fan sandstone of Lingshui Formation III, littoral-neritic sandstone of Sanya Formation and Meishan Formation, and reef limestone in the platform edge of Meishan Formation.