海底电缆资料处理关键技术及其应用

Key techniques for OBC data processing

对于浅海勘探中海底电缆(OBC)采集的地震数据,在处理过程中主要采用了初至波二次定位和双检波器数据求和等技术。初至波二次定位技术主要针对数据采集时电缆由海面向海底沉降过程中受海流影响而产生的位置偏离问题,即在已知炮点位置前提下,利用单炮记录初至波起跳时间、海水速度及炮检距等参数及其相互关系,采用二次定位技术可准确定位接收点在海底的实际位置。双检波器数据最佳求和技术是根据压力检波器(Hydrophone)标量特性和速度检波器(Geophone)矢量特性,采用上、下行波波场分离、GaussSeidel迭代等技术,求出各接收点地震波压力和速度能量之比,以此将压力检波器数据和速度检波器数据进行最佳比例求和,达到了压制虚反射和海水鸣震噪声的目的。

For seismic data collected by ocean bottom cable(OBC)in shallow water area,key processing techniques such as first-break based second positioning,and dual-sensor(hydrophone and geophone)data summation are widely used.First-break based second positioning is mainly applied to solve the position deviating problem of OBC which happened during the process of cable drop from sea surface to seabed.Usually,this problem is occurred due to ocean current.Based on known source positions,we can accurately determine OBC receiver positions with the relation among first break time,speed of ocean current,and offset.Dual-sensor data summation is used to eliminate ghost and ringing on seismic records.According to the scalar property of piezoelectric detector(hydrophone)and the vector property of velocity detector(geophone),the ratio of seismic wave pressure-to-velocity is calculated with wavefield separation and Gauss-Seidel iteration.Seismic data collected by dual sensors is summated based on the calculated optimum ratio.