基于结构约束的三维电阻率和重力法联合反演

Joint inversion of 3D resistivity and gravity method based on structural constraint

电阻率和重力法是两种重要地球物理勘探方法,为了充分发挥这两种方法各自的优势,并且减少单一方法反演多解性的问题,笔者采用一种基于交叉梯度约束的重力和电阻率法联合反演算法。通过惩罚项的形式将交叉梯度约束条件加入到联合反演目标函数中,并通过高斯牛顿法对目标函数进行数值求解。模型试算结果表明,联合反演相比于单独反演获得了结构相似性更高的模型,电阻率模型对密度模型的纵向约束较为有效,密度模型纵向分辨率明显改善,联合反演能够获得更加准确的异常体空间结构分布。

The resistivity and gravity methods are considered as two critical approaches in geophysical exploration.In order to maximize the advantages of each method and reduce the issues of multiple solutions in the single method of inversion,a joint inversion algorithm of gravity and resistivity methods based on cross-gradient constraints is applied in this thesis.For the inversion,cross-gradient constraints are included in the joint inversion objective function in penalty terms.The objective function is solved numerically by Gaussian Newton s method.The model trial results indicate that the joint inversion provides a more structurally similar model than the individual inversions.The resistivity model is considered to be more effective in constraining the density model longitudinally.The longitudinal resolution of the density model improved significantly,while the joint inversion could capture a more accurate spatial structure distribution of the abnormal body.