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Title: Comparison of stresses in 3D v. 2D geomechanical modelling of salt structures in the Tarfaya Basin, West African coast
Author: Hooghvorst, Jean Joseph
Harrold, Toby W. D.
Nikolinakou, Maria A.
Fernandez, Oscar
Marcuello Pascual, Alejandro
Keywords: Mecànica de roques
Prospecció electromagnètica
Visualització tridimensional
Àfrica occidental
Rock mechanics
Electromagnetic prospecting
Three-dimensional display systems
West Africa
Issue Date: 1-Feb-2020
Publisher: Geological Society of London
Abstract: We predict stresses and strains in the Tarfaya salt basin on the West African coast using a 3D static geomechanical model and compare the results against a simplified 2D plane-strain model. Both models are based on present-day basin geometries, are drained, and use a poroelastic description for the sediments and visco-plastic description for salt. We focus on a salt diapir, where an exploratory well has been drilled crossing a major fault. The 3D model shows a significant horizontal stress reduction in sediments at the top of the diapir, validated with measured data later obtained from the well. The 2D model predicts comparable stress reduction in sediments at the crest of the diapir. However, it shows a broader area affected by the stress reduction, overestimating its magnitude by as much as 1.5 MPa. Both models predict a similar pattern of differential displacement in sediments along both sides of the major fault, above the diapir. These displacements are the main cause of horizontal stress reduction detected at the crest of the diapir. Sensitivity analysis in both models shows that the elastic parameters of the sediments have a minimal effect on the stress-strain behaviour. In addition, the 2D sensitivity analysis concludes that the main factors controlling stress and strain changes are the geometry of the salt and the difference in rock properties between encasing sediments and salt. Overall, our study demonstrates that carefully built 2D models at the exploration stage can provide stress information and useful insights comparable to those from more complex 3D geometries
Note: Versió postprint del document publicat a:
It is part of: Petroleum Geoscience, 2020, vol. 26, num. 1, p. 36-49
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ISSN: 1354-0793
Appears in Collections:Articles publicats en revistes (Dinàmica de la Terra i l'Oceà)

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