摘要
电性源瞬变电磁法用于深部勘探时,观测到的垂直磁场脉冲响应非常微弱,常伴有严重的干扰噪声,从噪声中提取反映深部地层的中、晚期磁场信号非常重要。为此提出将多分辨率小波分析应用于电性源瞬变电磁法数据分析,并对西部某勘探区垂直磁场响应的迭前和迭后数据作多尺度分解后进行分析和比较的结果表明:①小波分析对数据具有良好的时频局部化特性,垂直磁场响应的迭前和迭后记录在不同频段上的分布特征可以清晰地反映出来;②高频干扰主要反映于数据的分解细节,反映深部信息的中、晚期弱信号存在于分解概貌;③迭后记录加入随机噪声与不加入随机噪声的处理结果类似,而迭前记录则不同,迭前记录比迭后记录具有更丰富的信息,并主要表现在早期。在电性源瞬变电磁法深部勘探中,利用更多的迭前记录的小波分解概貌对资料处理的解释工作很有意义。
The long-offset transient electromagnetic （LOTEM） method is a time domain electromagnetic sounding method, which measures induced electromotive force from source variation in loop receiver at distance using finite long grounded wire. The vertical magnetic-field impulse response on the surface of the earth is weak in deep exploration, which constantly submerges in noise and background signal. Therefore, it is important to extract the mid and late response to the magnetic field reflecting the deep stratum. In this paper, wavelet analysis is applied to the magnetic response, which is generally weaker than the electricfield response, and a comparison is made between the decomposed result of prestack record and that of stacked record on vertical magnetic response from CNPC＇s western exploration areas. The high frequency disturbance appeares in the wavelet detail part, while the mid and late response occurs in the wavelet approximation part. The result of stacked record with random noise is similar to that of stacked record without random noise. But it is different to prestack record, which contains richer information than the stacked record that mainly represents early stage. It is significant to make full use of the wavelet approximation of prestack record for the data processing and explanation of LOTEM deep exploration.
出处
《地质科技情报》
CAS
CSCD
北大核心
2007年第5期105-108,共4页
Geological Science and Technology Information
基金
中国石油天然气股份有限公司科学研究与技术开发项目(04B020500)
湖北省自然科学基金项目(2005ABA275)
关键词
长偏移距瞬变电磁法
多分辨率分析
小波变换
迭前
迭后
long-offset transient electromagnetic method （LOTEM）
multiresolution analysis
wavelet transform
prestack
poststack
