Inversion Research Of Gravity Gradient Tensor Based On Preconditioned Conjugate Gradient

Conventional gravitational exploration only surveys first-order vertical derivative of gravitational field,but gravity gradient tensor surveys second derivative of gravitational field,therefore compared with conventional gravitational exploration,gravity gradient tensor has better resolution,and reflects boundary of anomalous body clearly,which does good to draw the limit of ore body and geological body form.What’s more,gravity gradient tensor has five independent components,each of which has different information about anomalous body.Taking advantage of abundant information of gravity gradient tensor,five independent tensors are inverted jointly,which will decrease interpretation ambiguity and increase solution accuracy.Focused on the existing difficulties and problems in inversion of gravity gradient, it brings preconditioned conjugate gradient for it. Firstly, roughness function is added in the objective function to constrain underdetermined problems of which the number of parameters is far more than collected data. Secondly,depth weighting function is added in the objective function to compensate kernel function which diminishes rapidly with depth. Thirdly, every single component of gravity gradient is inverted,and compared inversion results of every single component. At last,joint-inversion of five independent measured components is made,inversion effect of which is better than every single component inversion.Five independent measured components are applied to invert synthesized model,inversion result shows that it coincides well with the real model, which demonstrates the merits of the algorithm.