Impact of the mechanical stratigraphy on fracture pattern predictions in reservoirs: Application of HCA numerical modeling to contractional structures.

It has long been recognised that a direct relation does exist between the kinematics of thrust-related fold evolution and the 4-D distribution of deformational features in the folds themselves. Templates of deformation patterns associated to contractional fault-bend and fault-propagation folding have been commonly produced by using geometrical modelling. This technique is only valid for roughly reproducing the first order distribution of deformational feature in fault-related anticlines, because it neglects the role of rock mechanics and rheology. Deformation patterns produced by geometrical modelling typically consist of an array of deformation panels limited by either active or fixed axial surfaces. The distribution of deformational features within deformation panels is assumed to be homogeneous. This is a major limitation when attempting to closely predict the actual distribution of deformational features, and in particular fracturing, in natural thrust-related anticlines. Mechanical stratigraphy exerts a first order control on deformation patterns in fault-related folds and can significantly alter the distribution of deformational features predicted by geometrical modelling. The fundamental impact of fracture distributions in hydrocarbon exploration and development imposes further efforts for substantially improving our predictive capability by implementing parameters such as mechanical stratigraphy in more sophisticated predictive tools. Our approach to the prediction of the geometrical and deformational architectures of fault-related structures includes the use of a specifically developed numerical tool, the Hybrid Cellular Automata (HCA). This real time forward modelling technique allows a step forward in the numerical simulation of the behaviour of natural rock multilayers undergoing deformation at shallow crustal levels, by merging specific properties of cellular automata and finite elements techniques, and by providing the possibility of simulating bed thickness lower than one centimetre. Input parameters used for describing the mechanical rock properties in the undeformed numerical multilayers are directly obtained from seismic datasets.In this contribution, we present results of HCA numerical experiments designed to highlight the impact of the mechanical stratigraphy on fracture predictions in reservoirs. In particular, we illustrate a working methodology for implementing quantitative fracture data from field analogues into HCA numerical models of fault-related folds imaged in reflection seismic profiles and developed in similar natural rock multilayers.