DISTRIBUTION PATTERN OF THE EARLY MIOCENE LARGE SHALLOW WATER DELTA IN THE WESTERN PEARL RIVER MOUTH BASIN AND ITS SIGNIFICANCE TO OIL AND GAS EXPLORATION

The western Pearl River Mouth Basin was topographically flat with abundant sediment sources in early Miocene when the Zhujiang Formation was deposited. Lithological sequences and seismic reflections indicate that after the large-scale transgression about 18.5 Ma ago, there occurred a large scale shallow water shelf delta as part of a highstand system tract. The basin had several sediment sources, when the Guangdong coastal rivers were wide, as indicated by the progradation of the deltaic sand bodies from northwest to southeast. In the places where delta front sands and pro-deltaic mudstone met, favorable reservoir-cap systems would be well developed. Influenced by the early uplifting of Shenhu, a variety of traps were formed, such as the drape anticline traps on the basement highs, the lithologic traps (lithological pinch-out trap and sand lens), and the structure-lithologic traps. Favorable exploration targets occur in the places where the formation of these traps matches well with the hydrocarbon generation, new tectonic movement and the formation of tectonic ridges since Neogene.