Improved realism of channel morphology in object modelling with analogue data constraints

Preserving realism of geological structures is a challenge for the reservoir engineer when history matching. Object based models offer the chance of enforcing realism but are hard to constrain to observed data. In this paper we present a novel approach for generating channels that is easier to match to observed data than the standard object-based approach. Our new technique uses Object Modelling as the first step, mimicking the geometry of fluvial sand channels. Object Modelling enables us to constrain channel geometry with analogue information of channel local orientation and dimension. However, the morphology of the output models is smoothed and the transition channel/no-channel zones are associated with uncertainty as they are not constrained by a variogram or multi-point statistics. The second step, Probability Field Simulation, adds realism in a final output model imposing a variogram to the transition zones. Probability Field Simulation preserves the channel geometry of the object models and shows a significant CPU advantage compared with currently available approaches. The new method was applied to a synthetic problem in which 3 different channel scenarios were considered: low density, high density, and high density with thin channels. The results show that the proposed method can handle this range of channel densities, and we can therefore assume that the approach could be implemented for different channel density data. A further important finding was that there is no significant difference between the CPU time for each case. In summary, our new technique is able to constrain object models to a variety of observed data types such as channels size, density and orientation, while showing significant CPU saving and preserving the geological realism of the matched model.