Hierarchical Fault and Fracture Prediction

Athmer, Wiebke; Bounaim, Aicha; Sønneland, Lars

Faults and fractures strongly influence the fluid flow in the reservoir and surrounding rock formations, and therefore understanding their distribution and density is crucial in the field of petroleum exploitation. In order to identify faults and fractures at various scales, a hierarchical approach is proposed comprising a combination of 3-D seismic mapping and extraction of large- to medium-scale faults, and small-scale and sub-seismic fracture prediction.

Prominent faults are mapped with different seismic attributes and highlighted using AntTracking technology. Depending on the quality of the seismic data, the application of 3-D Radon edge enhancement can further improve the capture of extensive faults. The identified discontinuities are then extracted following a point-cloud approach and translated into triangulated surfaces.

The small-scale fault and fracture prediction is performed with a geomechanical forward model in which the depth-converted seismic fault surfaces are imported. Boundary conditions such as 3-D remote stress and rock properties are applied on the faults to compute the perturbed paleo-stress field and hence predict the orientation of small-scale and sub-seismic faults.

The hierarchical workflow comprises different iterations of simulations with increasing number of input faults, establishing a feedback-loop and interdependency between the numerical model and the seismic interpretation. The output of the geomechanical forward model is thereby employed to validate the seismic edge volume before new faults are added to the forward model.

The simulation results can be used manifold, e.g. to identify fracture corridors, to better understand reservoir compartmentalization, and to improve 3-D geomechanical earth models.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013