浅层地震勘探数据拟同步采集时差分析与实践

Analysis of time difference in quasi-synchronous acquisition of shallow seismic data and its practice

理想的地震勘探数据采集,其硬件系统采用多道同步方式实现,保证多路信号的时间或相位一致性.理论时差分析表明,就地震信号的初至时刻来看,多路同步采集系统也存在系统误差.浅层地震勘探数据记录道数少,采用单个A/D模数转换器件通过逻辑系统控制实现少量地震道的多路循环分时采集,在满足采样定理所需采样频率和不增加地震信号初至系统误差的前提下,可以以较少的硬件成本实现浅层地震信号的有效采集,这种采集方式我们称之为有效拟同步采集;通过实践证明了其采集方式的有效性.

The data acquisition of ideal seismic survey is often realized by its hardware system using the multi-channel synchronous mode to keep time-consistency of multi-channel signal. Theoretical analysis of the time difference shows that the multi-channel synchronous acquisition system also has system errors in the pick of first arrive. The channel number of shallow seismic prospecting is not large, so we can use a logic system to control a signal A/D to collecting data channel by channel. It can realize data acquisition effectively with less hardware cost in the condition that the sample frequency satisfying the sampling theorem and not increasing the system error. This data acquisition mode is called effective pseudo synchronous acquisition. Its validity has been validated by practice.