GENETIC CHARACTERISTICS OF WAVE-DOMINATED DELTA: A CASE STUDY ON PLIOCENE YING Ⅱ MEMBER IN THE DONGFANG1-1 GAS FIELD，YINGGEHAI BASIN

Wave-dominated delta, also known as the beak-shaped or bow-shaped wave-dominated delta, has rarely been studied in literatures on its sedimentary characteristics. Taking the YingⅡMember in the Yinggehai Basin of the South China Sea as an example, based on the detailed analysis of logging, seismic and core facies, and combined with the sedimentary background of the study area, the genetic characteristics of sand bars of the wave-dominated delta are described in this paper. On the core facies, the wave-dominated deltaic sand bars are characterized by trough cross beddings with a small amount of lebensspur structures. In the logging curve it shows a series of continuous multiple reverse cyclic funnel-shaped sedimentary sequences. Low-angle progradational seismic facies are observed in bands or bow-shaped deposits. Based on the profile and plane views, it can be seen that the wave-dominated deltaic sand bars have a bow-shaped pattern in plane view, which is successively cut into three parts from west to east by mud flow channels, and the thickness of sand body increases progradationally. The wave-dominated delta is a destructive facies of a delta formed under the action of wave transformation when the wave action is stronger than the river.