基于物性参数梯度累加约束的电阻率法和重力勘探数据二维联合反演

Two-dimensional joint inversion of data of resistivity method and gravity exploration based on summative gradient constraint of physical properties parameters

对不同地球物理方法的数据进行联合反演,通过模型参数的相互约束可以减小反演的多解性.本文对电阻率法和重力勘探数据开展了基于电阻率和剩余密度梯度累加约束的二维联合反演研究.电阻率法采用数据空间Occam反演,重力勘探采用基于对数障碍法的正则化反演.通过在电阻率法和重力勘探反演的目标函数中引入电阻率和剩余密度梯度累加约束项,利用交替迭代方式实现了电阻率法和重力勘探数据的二维联合反演.对理论模型合成数据进行了单方法反演和联合反演,对比了反演效果.结果表明:联合反演结果优于单方法反演结果,联合反演结果对异常体的物性值恢复和形态刻画效果更好.

Joint inversion is a method to realize inversion by using a variety of geophysical data and mutual constraints of model parameters.Joint inversion of different geophysical methods can reduce the multiplicity through mutual constraints of model parameters.In this paper,the two-dimensional joint inversion of resistivity method and gravity exploration based on the summative gradient constraints of resistivity and residual density is studied.Resistivity method adopts data space Occam inversion,and gravity exploration adopts regularization inversion based on logarithmic barrier method.A disadvantage of common cross gradient is that the module of the cross-gradients is zero when one of the two gradients is zero,which is by definition when one of the two models is constant.An additive summative gradient structure coupling function can avoid this undesirable behavior,and this coupling constraint forces the gradients to be either parallel or antiparallel,depending on prior information about the sign of residual density-resistivity correlation.By introducing the summative gradient constraint term of resistivity and residual density into the objective function of resistivity method and gravity exploration inversion,the two-dimensional joint inversion of resistivity method and gravity exploration data is realized by using alternating iteration method.Our example designs single prism and different combination with different resistivity values.Single method inversion and joint inversion are carried out on the synthetic data of the theoretical model,and the inversion results are compared.Due to the addition of the prior information about the sign of residual density-resistivity correlation,summative gradient coupling is a strong coupling mechanism,which is very effective to improve theinstability of joint inversion.The results show that the joint inversion results are better than the single method inversion results,and the joint inversion results are better for the physical property value recovery and morphological characterization of anomalies.