Three-dimensional joint inversion of magnetotelluric and seismic travel time data with cross-gradient constraints
Three-dimensional joint inversion of magnetotelluric and seismic travel time data with cross-gradient constraints
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发表时间：
2013
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通讯作者：
T. Han
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作者：
T. Han
为了有效地克服大地电磁(或远震走时)单一反演的弱一致性，以及岩石物理方法的局限性，研究了一种具有交叉梯度约束的大地电磁和地震走时数据的三维联合反演算法。在成熟的三维远震和大地电磁正反演算法的基础上，实现了一种以交叉梯度为结构约束、具有共同反演网格的三维联合反演算法。利用单棱柱模型和双棱柱模型的合成数据，进行了联合反演的试算。结果表明，该算法具有较高的精度和较高的精度结果表明，与单一反演相比，联合反演对恢复单棱镜和双棱镜的空间形态都有更好的效果。单棱镜联合反演的电阻率值更接近真实模型，而双棱镜模型联合反演不仅在一定程度上消除了围岩的假电阻率异常，而且对提高异常体纵波深部结构的分辨率也有较大的提高。此外，在电阻率和速度不相容的情况下，联合反演改善了单独反演的结果，表明交叉梯度不受不同物性参数关系的限制。而是侧重于结构相似性，因而具有广泛的适用性。
To effectively overcome the weak consistency of single inversion of magnetotelluric(or teleseismic travel time data),and also to solve the limitations of petrophysical approach,we study a three-dimensional joint inversion algorithm of magnetotelluric and seismic travel time data with cross-gradient constraints.Based on well-developed three-dimensional teleseismic and magnetotelluric forward and inversion algorithms,a three-dimensional joint inversion algorithm having common inversion grids,with cross-gradient as structural constraint,and with both resistivity and velocity models able to be simultaneously obtained has been achieved.With synthetic data from a single-prism model and two double-prism models,trial computation of joint inversion has been carried out,and the results indicate that,compared with single inversion,joint inversion has better effect in recovering both single prism's and double-prism's spatial morphology.The resistivity value of the single-prism is much closer to the true model in joint inversion,while by double-prism models,joint inversion not only removes false resistivity anomaly of wall rock to a certain degree,but also has large improvement on increasing the resolution of P-wave deep structure of anomalous body.Moreover,joint inversion improve the separate inversion results when resistivity and velocity is incompatible,indicating the cross-gradient is not be restricted on the relationship of different petrophysical parameters,but rather focuses on structural similarity and thus has wide applicability.