多波地震勘探技术在海上气田构造成像中的应用

莺歌海盆地是南海北部大陆架重要的含气盆地,盆地中央沉降速度快且欠压实,局部构造发育.该盆地中央泥拱带浅层气很发育,加之深部热流体的影响,导致纵波剖面上出现模糊区和构造形态畸变(同相轴下拉),严重影响了勘探效果.由于转换波传播受气的影响远远小于纵波,故在转换波剖面上不存在模糊区,也不会出现构造形态畸变.因此,多波地震技术不仅可用于烃类检测,而且可用于构造的准确成像,这对气田的勘探开发有着重要意义.

APPLICATION OF MULTIWAVE SEISMIC TECHNIQUE IN STRUCTURE IMAGING IN OFFSHORE GAS FIELD

Yinggehai basin is an important gas-bearing basin in the northern shelf of South China Sea. Mud di-apiric structures developed in the central part due to rapid subsidence and undercompaction. There are large seismic obscure zone and severe structural distortion (eventdownwarping)on the p-wave sections because of the presence of the shallow gas reservoirs in central mud diapiric structure zone and the influence of the hot fluids from deeppart, which affected the exploration effects seriously. Because the influence of gas on the travel of s-waves is far less than p-waves, there are no gas chimney (p-wave obscure zone caused by the shallow gas reservoirs)and structural distortion on the converted s-wave sections. Therefore,the multiwave seismic technique is applicable not only for hydrocarbon detecting but also for accurately imaging of subsurface structures and has significance for hydrocarbon exploration and development.