Marine controlled-source electromagnetics-based technology for generating arbitrary-frequency waveforms
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摘要: 海洋可控源电磁(marine controlled-source electromagnetic, MCSEM)探测方法通过揭示海底以下的电性差异来探测油气和天然气水合物等资源, 以及深部地质构造。不同的激发频率对应不同的探测深度, 为了更好地对海底以下目标进行电性成像, 本文开展了海洋可控源电磁的任意频率波形产生技术的研究, 用于灵活改变激发频率, 提升勘探效果和效率。本论文基于直接数字频率合成(DDS)芯片AD9833, 通过单片机和复杂可编程逻辑器件(CPLD)联合调控, 可以在海洋可控源电磁探测中发射0～100 Hz的步进0.01 Hz的任意单频驱动信号, 实现了有限精度任意频率波形的产生。最后对测试技术指标进行分析后得出, 任意频率波形产生技术可以有效提高MCSEM的频谱适应性和灵活性。Abstract: Marine controlled-source electromagnetics (MCSEM) is used to explore resources such as oil and gas hydrates, as well as deep geological structures, by revealing resistivity differences below the seabed. Different excitation frequencies correspond to varying detection depths. To enhance the resistivity imaging of targets beneath the seabed, this study investigated the MCSEM-based technology for generating arbitrary-frequency waveforms to flexibly alter the excitation frequency and improve the exploration effectiveness and efficiency. Using the direct digital frequency synthesis (DDS) chip AD9833 and the joint control of a microcontroller and a complex programmable logic device (CPLD), this study achieved the generation of arbitrary-frequency waveforms with limited precision. The test results indicate that this technology can effectively enhance the spectral adaptability and flexibility of MCSEM.
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