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Abstract: Application of an Integrated Technique for Analysing Naturally Fractured Reservoirs

Marie Christine Cacas, Jean Letouzey, Madjid Badsi

We are evaluating a new technique for analysing and modelling natural fracture networks. We focus on fracture scale ranging between a tenth of meter to a few tens of meters. Joints and faults are considered, but these two classes of fractures are analysed with different techniques.

The modelling technique combines two descriptions of the medium, a global model and a local model:

1. The global model provides maps of the spatial distribution of locally averaged fracture attributes (average orientation, local density...); it follows a deterministic approach based on geomechanic numerical modelling, curvature analysis of 3D seismic horizons, interpolation of core and borehole data between wells, or analysis of analogue models.

2. The local model is a 3D object-oriented modelling of the fracture network at a given location pointed to in the global model. Stochastic modelling is used at this scale. The statistical parameters of the stochastic procedure are determined in such a way that the average values predicted with the global model are honoured by the local model. Data about the 3D architecture of the fracture network come from outcrop studies, or rules concerning the different fracture network morphologies observed in the geological media.

This methodology, applied here to a test case of fractured reservoir with field analogues available, appears to be more predictive than usual approaches for fracture analysis. By combining two scales of analysis, it provides answers in both fields of field development and reservoir engineering.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela