Deriving 3-D Structural Geology Data From Full Tensor Gravity Gradiometry: A Case Study From a Rift System

Abstract

Gravity gradiometry has an increasingly important role to play in minerals and petroleum exploration, particularly for facilitating automated structural analysis and the building of 3D geological boundaries and structural surfaces. To optimize use of this full tensor data, we propose a new method for 3D geology feature extraction directly from the components of the full tensor signal. Our technique finds strike and dip pairs for geological and fault contacts. Gravity profile data crossing a fault can be used to estimate the dip, block thickness and density contrast across the structure. The strike is found using standard edge detection methods. An upward continuation strategy is employed. At each step, a double horizontal derivative is calculated so that a zero cross-over point, offset from the fault toe, can be found. This offset is then used to find the dip (the signal is in effect operating on Gxz). A progression towards a viable technique has been occurring over several years and is not being done in isolation, but rather by leveraging upon several key new technologies in related fields. This paper will explain some of the background and related work for this new technology. We will demonstrate the new technology with a case study from a rift system where the gravity gradiometry signal is unambiguous, strong and some existing structural knowledge is available to help calibrate the results.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015