柴达木盆地三湖地区表层低速带引起的地震异常判识及消除

柴达木盆地三湖地区近些年进一步的勘探实践发现,该区地震异常特征并不完全预示地层含气。经分析研究认为,该区地震异常从成因角度可分为3种类型:一是表层低速带(非含气)引起的地震异常;二是由高丰度气引起的地震异常;三是由低丰度气与表层低速异常带共同引起的地震异常。地震正演模拟和反复实验证明,应用共炮检距剖面分析技术能够有效判识研究区表层低速异常带引起的地震异常,在此基础上联合应用层析成像静校正技术与叠前深度偏移处理技术,能够较好地将其消除。

Identification and elimination of seismic anomalies caused by surface low-velocity zone in Sanhu area,Qaidam Basin

In recent years,further exploration practice in Sanhu area of Qaidam Basin discovers that not all the seismic anomalies are caused by gas in reservoirs. After deeply analysis,the seismic anomalies can be divided into three groups according to the genesis. The first type is caused by surface low-velocity zone (non-gas). The second type is caused by the high-abundance gas. The third type is caused by the above two facts. Seismic forward modeling and repeated experiments show that common offset profile analysis technique can effectively identify the seismic anomalies caused by surface low-velocity zone. After identifying this type of seismic anomalies,by jointly applying seismic tomography static correction and pre-stack depth migration,the seismic anomalies can be eliminated.