中心回线TEM勘探设计中观测时间和信噪比估算
Evaluation of measuring time and signal-noise ratio in central loop TEM design
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摘要: 收集探测深度范围内全套地层的电测井资料、正演感生电动势EMF (Electromotive Force)衰减曲线和反演观测时间,根据噪声电平和发射机最大输出电压及导线电阻,确认与最大发射电流有关的发射回线边长,是中心回线TEM (Transient Electromagnetic)法勘探设计中的重要内容,也是保证探测深度,取得高质量数据,完成地质任务的重要环节。山西王家岭工程表明,在质量良好的实测曲线基础上,可以获得地层层次分明、地质构造清晰的电性反演剖面。进一步指出,取得各层位、井下各地段水样的电阻率值,可以为水文地质地球物理探测前提的论证提供更充分的依据。Abstract: Evaluation of induced electromotive force by forward modeling based on collection of full set stratigraphic conductivity logs, and measuring time by inverse modeling, determination of loop size relative to maximum output current according to noise level, maximum voltage of transmitter and wire resistivity are important contents for designing transient electromagnetic sounding, ensuring detecting depth, acquisition of good data and completion of geological exploration. Wangjialing project in Shanxi Province shows that the electrical section with distinct stratification and structure would be obtained due to good data. Further more, to acquire resisticity of water sampled from varied layers in earth and zones in mine could provide more sufficient grounds for demonstration of geological prospecting in hydrological exploration.