Seismic Facies Characteristics and Sedimentary Facies Evolution of Wenchang Formation in Transfer Zone of Fault A in Huizhou Sag

Huizhou sag locates in the middle of northern depression belt of the Pearl River Mouth Basin,which is one of the richest hydrocarbon-bearing depressions in eastern South China Sea.It ′s difficult to make plane research of the sedimentary facies through single well facies only for low exploration degree and few drilling information in the Wenchang formation of Huizhou sag.By analyzing and contrasting the 3D seismic section, the Wenchang formation can be divided into SQ1-SQ4 four seismic sequences in transfer zone of fault A of Huizhou sag.After the research of the seismic facies of the transfer zone of fault A,wedge-shaped seismic facies,foreset seismic facies,sill-like parallel-subparallel seismic facies and lens seismic facies are identified on the seismic sections.And the distribution range of the seismic facies on the plane is known.Based on the thorough research of the sedimentary facies in every sequence of Wenchang formation drilled by single well, the seismic facies may be inverted to sedimentary facies under the regional geological background.Distribution and evolution characteristics of the sedimentary facies in sequences of Wenchang formation are analyzed.It is found out that the sedimentary facies includes braided river delta,fan delta,shore-shallow lake and semideep-deep lake facies,among them the braided river delta is the most important sedimentary facies in this area.