井间电磁成像测井系统分析与研究

Analysis and Research of Cross-well Electromagnetic Imaging Logging System

以电磁场理论为基础,研究井间电磁感应幅度与相位的正反演模型与算法。分析EMI公司XBH-2000井间电磁成像测井系统与斯伦贝谢公司Deeplook-EM井间电磁成像测井系统的优缺点,针对井间电磁测井中发射天线、接收天线与微弱电磁感应信号采集处理展开研究。提出发射部分采用低压储能、磁偶极子定向谐振发射以及幻相电缆平衡供电等技术,接收部分采用GPS综合同步相位检测、锁相放大、自适应取样积分、共模抑制、温度补偿校正与天线刻度等信号检测与处理技术。该研究有效提升了电磁波发射效能,提高了信噪比,为仪器研制奠定了理论基础。

On the base of electromagnetic field theories, we study the forward and inversion model and formulas for amplitude and phase of cross-well electromagnetic induction. By analyzing advantages and disadvantages of the existing cross-well electromagnetic systems XBH-2000 from EMI company and Deeplook-EM from Schlumberger, further studies are conducted for transmitting antenna, receiving antenna, weak-signal collection and processing. A range of technologies are used in the transmitter, such as low-voltage energy storage, resonance transmission and directional transmission of magnetic dipole, phantom balanced power supply for logging cable. Furthermore, the technologies for signal detection and processing are used in receiver, including GPS and integrated synchronization, phase lock in amplifier, adaptive sample integral, common-mode rejection, temperature compensation and correction as well as antenna calibration. Then, the efficiency of transmission and signal-to-noise ratio are improved significantly. All these studies provide theoretical foundation for the development of cross-well electromagnetic system.