大地电磁面积性资料和稀疏测线资料的三维反演解释

3D Interpretation of Magnetotelluric Sparse Survey Lines Data and Dense 3D Grid Data

对理论模型合成的稀疏测线数据和面积性数据以及实测单一测线数据进行了三维反演。通过对比分析合成稀疏测线数据和面积性数据的三维反演结果发现,使用4个张量阻抗元素作为反演数据的稀疏测线数据的三维反演结果可以较好地反映三维目标体,虽然效果可能不如面积性数据的三维反演结果。实测单一测线数据的三维反演结果也较好地揭示测线周围地下基岩界面的三维起伏情况。合成数据和实测资料的三维反演结果表明:可以采用三维反演解释的方法对大地电磁稀疏测线资料进行反演解释。同时,从合成数据的三维反演结果分析可以看出,对大地电磁稀疏测线资料进行三维反演,应尽可能反演所有张量数据;对大地电磁面积性资料进行三维反演,可以只使用两个非对角元素数据,但使用所有张量数据的效果更好。

We inverted the synthetic sparse survey lines data and dense 3D grid data generated from the test models and the field single line data.From the comparison between the 3D inversion results of synthetic sparse survey lines data and the 3D inversion results of dense 3D grid data,it is found that the 3D inversion results of synthetic sparse survey lines data can recover the 3D target although the effect is not as good as the 3D inversion results of dense 3D grid data.The 3D inversion results of the field single line data well reflect the 3D information of the bedrock interface underground near the survey line.The 3D inversion results show that it is possible to interpret MT sparse survey lines data using 3D inversion method.From the analysis of 3D inversion results from the synthetic data,all the tensor elements are suggested to be used in 3D inversion to interpret the sparse survey lines data and two off-diagonal elements can be used in 3D inversion to interpret the dense 3D grid data,while the results are better when all the tensor elements are used.