--> 3-D Structural Modeling and Restoration of the Western Sicilian Fold-and-Thrust Belt

AAPG ACE 2018

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3-D Structural Modeling and Restoration of the Western Sicilian Fold-and-Thrust Belt

Abstract

Three-dimensional modeling is a common exploration tool used in Oil & Gas industry. It allows the reconstruction of the deformation history of a sedimentary basin. 3D structural models describe the geometry and layout of rocks units in three-dimensional space, honoring available observations, measurements, seismic interpretation and geological concepts. On the other hand, restoration is one the existing techniques used to validate the structural interpretation of a geological unit defining if the model is geometrically consistent. In the Oil industry this technique is used to reduce the exploration risks validating the model.

The Sicilian Fold-and-Thrust Belt represents a structurally complex area where is possible to observe variation of shortening, exhumation, syn-tectonic sedimentation and structural style along strike. 3D model reconstruction in such complex area can represent a real challenge linked to unclear or incomplete data (2D onshore seismic lines) and because the complexity makes several scenarios possible. To lead a correct interpretation, the restoration represents a valid tool.

The study area is located in western Sicily and extend about 870 km2. Seismic interpretation was performed along 12 seismic lines and the 3D structural model was reconstructed using Skua-GoCad 2017 based on seismic interpretation and field data. The interpreted horizons are: the top of Cretaceous Amerillo formation and the top of the Miocene deposits which represent the autochthonous unit and the top of the deep-water deposits and the top of the foredeep deposits which represent the allochthonous units. Faults showing the higher displacement were represented.

A variation of the structural style along strike is recognized: from south verging structures in the western part to north verging structures in the eastern one. Two 3D structural models can be proposed based on the seismic interpretation: a single or a two-step thrust-fault tectonic phases. The geomechanical restoration of the autochthonous unit of these structural models was performed using the GoCad Kine3D3 tool, in order to validate which one represent the best solution.

Keywords: 3D structural model, restoration, Sicilian Fold-and-Thrust belt, seismic interpretation, GoCad, Kine3D