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Apparent Terrain Density Estimations with Variable Terrain Corrections Using Stochastic Inversion
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 78th EAGE Conference and Exhibition 2016, May 2016, Volume 2016, p.1 - 5
Abstract
Summary
A new method for estimating apparent terrain densities and computing a variable terrain correction has arisen from consideration of the separation of an apparent density contrast effect due to the terrain interface, to the effect of geological density contrasts in the near subsurface on the observed gravitational signal. The method involves an equivalent source or half-space 3D density inversion to predict densities. Statistical correlation methods for estimating terrain density can provide average terrain correction densities but not whole-survey variable estimations. Stochastic full tensor inversion of a 3D density voxet with a mean equivalent to the average terrain correction density and a broad property distribution can produce a consistent variable density terrain correction (VTC) and an optimised apparent terrain density 3D voxet.
If the input to the inversion is the gravity response of the terrain, ie the average terrain correction itself, then the forward response tensor grid of the optimised 3D density voxet is itself a VTC. By vertically averaging the 3D density voxet we get a 2D apparent terrain density grid which reflects the terrain. This method is independent of near-surface geology effects and only due to terrain. Applications are potentially widespread and show great promise in exploration.
© EAGE Publications BV