3维VSP光纤检波器井下地震采集系统

Down-hole Seismic Survey System with Fiber-optic Accelerometer Sensor for 3-Dimensions Vertical Seismic Profile

介绍了一种用于石油勘探的井下3维VSP(Vertical Seismic Profile)采集系统设计方案,实验验证该系统达到了可测量动态范围80dB(可测量最大值与最小之比),系统采集、处理和传输的总延时低于200ms(2kbit/s采样率)的指标,适用于井下VSP采集.系统采用六级光纤加速度传感器组成阵列,其中每级传感器由三个麦克尔逊干涉仪构成.使用高速DSP处理芯片实现相位产生载波(Phase Generated Carrier,PGC)解调等算法以获得地震波信号;同时应用多个ARM处理器设计光纤检波器阵列控制器以及阵列内部总线.

A down-hole seismic survey system that can be applied in three dimensions vertical seismic profile （VSP） detection in petroleum exploration is demonstrated. The results of experiments show that the system has a dynamic measurement range of 80dB （ratio of maximum to minimum value） and the total delay for signal collection,process and communication is less than 200ms @ 2k bit sample rates. An array consisting of six fiber-optic accelerometers （receivers） is applied in this system. Each receiver is comprised of three fiber-optic Michelson interferometers. High-speed DSP chips are employed to realize the PGC demodulation and other algorithms to obtain the seismic information. Multi-ARM CPUs are introduced into the system to design the fiber-optic accelerometer array controller and the receiver array local bus. The design and experiments of the system are given in this paper in detail.