Joint inversion of geologically realistic, synethetic earth models

Carter-McAuslan, Angela Elizabeth (2013) Joint inversion of geologically realistic, synethetic earth models. Masters thesis, Memorial University of Newfoundland.

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Abstract

Inversion modelling problems are ill-posed and non-unique and, as such, they have an infinite number of potential mathematical solutions. By using the joint inversion of two different but complementary geophysical datasets a model can be produced in which there can be a greater degree of confidence. To test the joint inversion methodology a code for the modelling of borehole seismic tomography and gravity data was used to attempt to reproduced geologically-realistic synthetic Earth models. A number of 2D and 3D synthetic Earth models, based on the geology of the Eastern Deeps zone of the Voisey's Bay deposit in Labrador, were constructed. These models consist of unstructured triangular and tetrahedral meshes. The 2D models were based on conceptualized models of the Eastern Deeps and are varied in complexity. The 3D tetrahedral model was built based on Datamine wireframe model of the Eastern Deeps. Single property and joint inversions were carried out to evaluate the ability of the joint inversion methodology to reproduce the models and to determine which inversion parameters were most crucial in generating the best inversion results. Through these tests it has been shown that the joint inversion code was able to locate a buried high contrast target in 2D and 3D cases. During 3D tests it has been concluded that a balance between the noise levels, number of cells in the inversion mesh, seismic acquisition array and gravity measurement locations had to be carefully considered in light of the available memory capacity and computation time in order to attain reasonable joint inversion results.

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