Uncertainty studies become increasingly important as reservoir complexity increases. Although such studies are commonly a key factor in oil and gas exploration, projects are commonly restricted to simulation of facies and petrophysical properties. The structure of the reservoir itself is commonly considered to be a deterministic parameter, and yet it may contain uncertainty that has a major impact on the reserve estimations.

A new methodology based on the P-field technique and focusing on reservoir geometry uncertainty is proposed to tackle this problem. With this method, not only horizon but also fault geometries are simulated around a given reference model.

Because simulating fault geometries is more difficult than simulating horizon geometries, a new data structure has been designed to produce efficient computation of geometries. The simulation method tries to preserve the initial geometry at best. It may affect the location, dip, and shape in map view of all faults or any combination of these three basic modifications. Then, for each fault network realization, several horizon geometry simulations may be performed. The modeling and simulation system keep the geological model consistent after each simulation loop, allowing volumetric studies to proceed in a consistent fashion.