多道瞬变电磁法共中心点道集数据联合反演

多道瞬变电磁法是目前地面资源勘查领域的研究热点,开展该方法观测数据的一维反演对完成装备研发及技术推广具有积极的推动作用.针对多道瞬变电磁法特殊的源波形和数据采集方式,本文对多道瞬变电磁数据的响应提取和一维反演进行了研究.首先,采用反卷积方法从伪随机二进制序列全波形响应数据中提取大地脉冲响应.为了避免脉冲响应中空气波的干扰,提出采用反向积分算法,把脉冲响应转换成下降沿阶跃响应,并将其整理成共中点道集.最后,为充分利用各个偏移距下的响应数据对不同深度范围目标体的分辨能力,采用基于OCCAM算法的联合反演方法对共中心点道集数据进行联合反演.结果表明在不同目标体深度以及有噪声干扰的情况下,共中心点道集数据联合反演计算均可获得较好的结果.

Joint inversion of CMP gathers of multi-channel transient electromagnetic data

The multi-channel transient electromagnetic (MTEM) method is one of the research focuses of prospecting for underground mineral resources. The study of the 1D inversion of MTEM data will promote the development of the instrument and theory of the methods. Based on the pseudo-random binary sequence (PRBS) source waveforms and configurations of the MTEM method, this paper presents the processing and inversion methods of MTEM data. Firstly, the earth impulse response of PRBS is obtained by deconvolution. Then step-off responses recovered from the impulse responses by reversed integration are sorted into common mid-point (CMP) gathers. Finally, the joint inversion scheme based on OCCAM inversion is tested on the CMP gather data. The results show that the inversion of CMP gathers can obtain good results at different depths with presence of noise.