Potential field migration for rapid 3D imaging of entire gravity gradiometry surveys

Abstract

The geological interpretation of gravity gradiometry data is challenging. With the exception of the vertical gradient, maps of the different gravity gradients are often complicated and cannot be directly correlated with geological structure. 3D inversion has been the only practical tool for the quantitative interpretation of gravity gradiometry data. However, it is a complicated and time-consuming procedure that is very dependent on the initial model and constraints used. To overcome these difficul- ties for the initial stages of an interpretation workflow, we introduce the concept of potential field migration and demon- strate its application for rapid 3D imaging of entire gravity gradiometry surveys. This method is based on the direct integral transformation of the observed gravity gradients into a subsurface density distribution that can be used for interpretation, or as an initial model for subsequent 3D regularized inversion. We present a case study for the interpretation of gravity gradi- ometry data acquired in the Nordkapp Basin. We find agreement between the results obtained from potential field migration and those obtained from 3D regularized inversion, and show that the migration result are comparable to smooth inversion. For regional-size datasets, runtimes for migration are in the order of minutes compared to hours for inversion.