海洋可控源电磁法一维正演响应分析与反演研究
发布时间：2018-10-31 19:20
【摘要】：本论文以海洋可控源电磁法(Marine Controlled-source Electromagnetic Method,MCSEM)中的经典一维层状地电模型为基础,深入讨论了电偶极子场各分量的正演响应特征,研究了在不同发射-接收装置方位、不同场分量和不同频点下的正演模拟数据对理论模型反演的分辨率影响,最后仿真模拟出了实际海水层和海底地层电阻率变化情况下的反演特征。在电磁场的正演计算中,使用TE、TM模式分解的方法,引入谢昆诺夫势分别对不同方位电偶极子产生的电磁场进行了计算;综合分析场分量得到:无论何种发射-接收方位下,五层含油气层模型与三层模型振幅对比时,Ey、Ez和Bx分量的异常都比Ex、By和Bz的异常大;分析了空气波影响因素,海水的深度对空气波的压制起到了很大的作用,相同的海水深度下海底电阻率不同时,空气波开始影响的临界收发距不变,而海底地层电阻率越高,空气波占优的临界收发距越大;研究了覆盖层厚度的影响,对于1 Hz的电磁波,覆盖层大于3000m时海底高阻产生的异常开始消失;验证了振幅-收发距(Magnitude Value Offset,MVO)曲线的T等值现象,在固定厚度和电阻率的乘积不变时,MVO曲线几乎重合;最后正演计算了浅层薄层高阻屏蔽的情况发现:加大收发距可以得到深层的异常体信息。在反演的计算中,引入了高斯-牛顿反演法和奥克姆反演法进行对比,然后利用奥克姆反演法分别分析各发射方位、各分量和不同频点组合的一维反演效果发现:HED-Y模式下的数据反演效果最好;使用Ey和Bx分量进行反演效果最好,z分量的电磁场的反演效果较差,联合反演Ey、Ez和Bx的数据对反演效果没有更好的提升,反演经典五层模型时,0.1 Hz和1 Hz的频点组合进行反演就达到了良好的效果,继续增加频点来反演也没有提高反演效果。在最后仿真模拟海洋地层的反演时发现:海水电阻率分层对反演效果影响很大,测量海水电阻率分层是必要的,海底地层电阻率小尺度变化时,反演结果能反映出海底地层电阻率变化的趋势。
[Abstract]:Based on the classical one-dimensional layered geoelectric model of ocean controllable source electromagnetic method (Marine Controlled-source Electromagnetic Method,MCSEM), the forward response characteristics of each component of electric dipole field are discussed in depth, and the azimuth of different transmitter-receiver devices are studied. The effect of forward modeling data at different field components and different frequencies on the resolution of the theoretical model inversion is obtained. Finally, the inversion characteristics of the actual seawater layer and submarine strata are simulated. In the forward calculation of electromagnetic field, using the method of TE,TM mode decomposition, the electromagnetic field generated by electric dipole with different azimuth is calculated by introducing Shikhunov potential. It is concluded by comprehensive analysis of field components that the anomalies of Ey,Ez and Bx components are larger than those of Ex,By and Bz when the amplitudes of the five-layer oil-bearing gas reservoir model and the three-layer model are compared with those of the three-layer model under any emission-receiver azimuth; The influence factors of air wave are analyzed. The depth of sea water plays a great role in the suppression of air wave. The larger the critical transceiver distance of air wave is; The influence of overburden thickness is studied. For the electromagnetic wave of 1 Hz, the anomaly caused by high resistivity of seabed begins to disappear when the overburden is larger than 3000m. The T-equivalent phenomenon of amplitude-transceiver distance (Magnitude Value Offset,MVO) curve is verified. When the product of constant thickness and resistivity is invariant, the MVO curve almost coincides. Finally, the forward calculation shows that the deep abnormal body information can be obtained by increasing the transceiver distance. In the calculation of inversion, Gao Si Newton inversion method and Oakham inversion method are introduced to carry out the comparison, and then each launch azimuth is analyzed by using the Oakham inversion method. The results of one-dimensional inversion of different components and different frequency points show that the data inversion effect of HED-Y model is the best; The inversion effect of Ey and Bx components is the best, the electromagnetic field inversion effect of z component is poor, and the inversion effect of Ey,Ez and Bx data is not improved better. The combination of 0. 1 Hz and 1 Hz has achieved a good result, and the inversion effect has not been improved by increasing the frequency points. When simulating the inversion of marine strata, it is found that the resistivity stratification of sea water has a great influence on the inversion effect, it is necessary to measure the stratification of resistivity of sea water, and when the resistivity of seabed strata changes on a small scale, The inversion results can reflect the trend of the resistivity variation of the submarine strata.
【学位授予单位】：东华理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.325
本文编号：2303291
[Abstract]:Based on the classical one-dimensional layered geoelectric model of ocean controllable source electromagnetic method (Marine Controlled-source Electromagnetic Method,MCSEM), the forward response characteristics of each component of electric dipole field are discussed in depth, and the azimuth of different transmitter-receiver devices are studied. The effect of forward modeling data at different field components and different frequencies on the resolution of the theoretical model inversion is obtained. Finally, the inversion characteristics of the actual seawater layer and submarine strata are simulated. In the forward calculation of electromagnetic field, using the method of TE,TM mode decomposition, the electromagnetic field generated by electric dipole with different azimuth is calculated by introducing Shikhunov potential. It is concluded by comprehensive analysis of field components that the anomalies of Ey,Ez and Bx components are larger than those of Ex,By and Bz when the amplitudes of the five-layer oil-bearing gas reservoir model and the three-layer model are compared with those of the three-layer model under any emission-receiver azimuth; The influence factors of air wave are analyzed. The depth of sea water plays a great role in the suppression of air wave. The larger the critical transceiver distance of air wave is; The influence of overburden thickness is studied. For the electromagnetic wave of 1 Hz, the anomaly caused by high resistivity of seabed begins to disappear when the overburden is larger than 3000m. The T-equivalent phenomenon of amplitude-transceiver distance (Magnitude Value Offset,MVO) curve is verified. When the product of constant thickness and resistivity is invariant, the MVO curve almost coincides. Finally, the forward calculation shows that the deep abnormal body information can be obtained by increasing the transceiver distance. In the calculation of inversion, Gao Si Newton inversion method and Oakham inversion method are introduced to carry out the comparison, and then each launch azimuth is analyzed by using the Oakham inversion method. The results of one-dimensional inversion of different components and different frequency points show that the data inversion effect of HED-Y model is the best; The inversion effect of Ey and Bx components is the best, the electromagnetic field inversion effect of z component is poor, and the inversion effect of Ey,Ez and Bx data is not improved better. The combination of 0. 1 Hz and 1 Hz has achieved a good result, and the inversion effect has not been improved by increasing the frequency points. When simulating the inversion of marine strata, it is found that the resistivity stratification of sea water has a great influence on the inversion effect, it is necessary to measure the stratification of resistivity of sea water, and when the resistivity of seabed strata changes on a small scale, The inversion results can reflect the trend of the resistivity variation of the submarine strata.
【学位授予单位】：东华理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.325
【参考文献】
相关期刊论文 前2条
1 何继善,鲍力知;海洋电磁法研究的现状和进展[J];地球物理学进展;1999年01期
2 李予国;段双敏;;海洋可控源电磁数据预处理方法研究[J];中国海洋大学学报(自然科学版);2014年10期
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