关键词: 西湖凹陷, 中深层, 地震勘探阶段, 二次三维地震, 两宽一高一多

Abstract: The Xihu sag in the East China Sea Shelf Basin has distinctive seismic geological features - such as deep layers, serious multiples, thick and heterogeneous sandstone, or thin sand-mud-coal interbeds - which restrict deep exploration. Analysis of the factors controlling the quality of seismic data, as well as key seismic acquisition parameters and actual recorded seismic data, show that the seismic acquisition process in the Xihu sag can be divided into three stages. In the early stage (2D seismic exploration), the objective of seismic acquisition was to evaluate the sag structures and zones. Acquisition parameters developed from ‘short streamers and small seismic source capacity’ to ‘long streamers and large seismic source capacity’. In the middle stage (3D seismic exploration), the objective of seismic acquisition was to evaluate key exploratory blocks. Experience of different acquisition technologies was applied, from conventional 3D acquisition to Q-marine technology and acquisition technology using streamers with dual sensors. In the current stage (secondary 3D seismic exploration of key oil and gas fields), seismic acquisition technologies, such as ‘slant-streamer, wide-band and wide azimuth’ acquisition, ‘high-density and wide azimuth’ acquisition and non-zero offset VSP technology, have been studied and deployed in middle-deep strata in key target blocks. Thus, a series of secondary 3D seismic exploration technologies, characterized by wide-band, wide azimuth, high density and multiple components (2W1H1M), have been developed for seismic acquisition in middle-deep strata.